Why were so many people against the idea of a school of friendship? Is "you can't learn about friendship in a classroom" really that much of a justification for hatred and mockery?

I can't really speak for other people's opinions on the matter. For me personally I don't have an issue with the idea of a School of Friendship, I just felt like the execution was a bit sloopy, especially by making the Mane6 teachers there, on top of everything else they've got going on in their lives. I think a better way to handle it would've been for the teachers to be secondary characters that have learned about friendship from the Mane6, and maybe occasionally the Mane6 come in as guest speakers. And, admittedly, a school focused story feels a bit like a downgrade in terms of story and world focus compared to other avenues that the story could have gone, but for me the School of Friendship is largely saved as a concept by the Student Six themselves, who I actually rather enjoyed as characters. So I don't hate the idea or anything, I just felt like it could have been done better, and wasn't necessarily the best concept for something that's feature in the last seasons of the show when I much rather would have preferred wider explorations of the world as a whole.

7253527
Wow, you nailed it. When I saw this question posted, I wanted to give a balanced answer. But I wasn't sure about how to understandably sum up my feelings, or if I had the time. Then I see you preemptively came to my rescue.

7253523
From what I remember seeing the biggest objections tend to be less about "teaching" friendship in general, and more about the conceit that all of the various non-pony races needed to be "taught" friendship in the first place... the implication being that friendship somehow didn't exist outside of Equestria. It painted a pretty bleak image of the larger world at beast, or worse presented ponies as incredibly arrogant for forcing their ideas and values onto other cultures.

Now, I think the latter interpretation can be mostly debunked in that participation in the school by other races was clearly entirely voluntary. As for the other races lacking an understanding of basic friendship, I always took it as the friendship Twilight wanted to spread was specifically the "Magic of Friendship" as made manifest by the combined virtues and principles represented by the elements of harmony. It's not that the other races were entirely ignorant of the concepts individually, but as the song goes... "and MAGIC makes it all complete!"

7253527
Granted, yes, it does stretch credulity that the Mane-Six could find time to ad teaching an entire school of students, I feel it actually was a fairly natural progression of the show's themes. The show had already been struggling with repetitiveness, with the Mane-Six seemingly having to relearn the same lessons in friendship multiple times over. In my opinion it's a far better fit to ship them into a teaching role where they can begin passing on those lessons to a next generation, and I do think it had to be the Mane-Six themselves taking on those roles and not just other side characters they've helped in previous episodes. They are the MAIN characters and this is THEIR show, so they needed to remain front and center as the stars.

As for wanting to see the wider world "explored", while I can appreciate and even agree with that desire, I think that Twilight's school of friendship might actually have been the best way to do that. The show was always very Ponyville-centric, and it would have been an even greater paradigm shift if the Mane-Six suddenly started traveling all over the world all the time. Not to mention as hard as it might seemingly be for the Mane-Six to add teaching on top of their various careers and other activities, it'd be even harder to balance their regular live if they were constantly traveling. So instead of sending the Mane-Six abroad, the show brought the world to Ponyville, or at least select representatives.

Now, that said, while the student-six were great, I do think the concept could have been fleshed out better if they were just the focal members of their respective races at the school, not seemingly the ONLY members. It certainly could have provided more opportunity to highlight their bond as a group made up of different races, if there had been contrasting background characters of differing races all shown mostly sticking to their own kind. As it stands with all of them being "outsiders" to Equestria, it seems almost natural for them to form their own little clique over their shared commonality of all being far from home.

7253523
I think @thatguyvex hit the metaphorical nail on the head, it's not so much the concept or the idea, its the fact that it was shoved into the second to last season of the show with pretty much no buildup beforehand, and the Mane Six suddenly having the time and resources (not to mention skills) to teach on top of everything else. I also agree with him that the Student Six were more often than not the best part of season eight, the Mane Six...not so much. I get that life lessons are not a one and done deal, but in all the seasons before it was two steps forward one step back, which I suppose is reasonable enough, but several episodes in season eight it was half a step forward, eight gallops back.

Also, I cannot remember exactly, but I think I was talking to someone else about this issue, and they told me "not learning Friendship from a book" is actually one of the most famous and pervasive myths in the fandom, Celestia actually never said that. She did tell Twilight to not spend all her time with dusty old books, but somehow that line got twisted in a telephone game sort of way into the highlighted line above.

7253527
This pretty much entirely. The Mane Six being teachers, I just can't buy. It breaks my SoD something fierce. I love the Student Six, mind,, and the general concept as sort of an almost Babylon Five for the School, where the various species go to meet and learn about each other.

7254063

. I love the Student Six, mind,, and the general concept as sort of an almost Babylon Five for the School, where the various species go to meet and learn about each other.

That's what I kind of liked about the whole idea. For me, learning about friendship was just learning how to be diplomatic, learn from each other, about the other cultures. Because let's face it...Equestria was kind of isolated in general as they rarely knew anything about the other cultures.