I agree with the topic creator that there are flaws. Sometimes, they're plotholes, sometimes they're inconsistency, and sometimes they're story lines that don't have the effect the writers think they do. It's good that there are whistleblowers to point out such things. However, if you use such scrutiny for any show ever made, and even movies, you're going to find similar flaws.
Take other shows that were similarly popular in their time, like Teenage Mutant Ninja Turtles, Arthur, and Pokemon season 1, you'll find similar errors. Teenage Mutant Ninja Turtles has characters with such static, stagnant personalities, that you'll find it hard to believe that they're as competent as they are when it comes to martial arts. In Pokemon, other than Ash being naive, Brock being a playboy, and Misty being naggy, their personalities change whenever it's convenient for the plot. Neither of those shows have aged well in my honest opinion, despite me being more addicted to them back in the day than I ever was to Friendship is Magic. (If you want to see a children's show similar to My Little Pony: Friendship is Magic that HAS aged well, check out The Busy World of Richard Scarry.)
The draw we have to Friendship is Magic, however, isn't that it's perfect. It's that it's still a notch above the majority of cartoons out there. It really does pull off characterization better than almost anything I've ever seen from that age group, from any generation. Subtle things such as facial expressions in critical plot moments reinforce this. While it does have issues that the topic creator pointed out, those aren't things that similar shows lack.