There's something to be said for Lauren Faust growing up with the original version of My Little Pony from 1981, seeing two iterations happen that she didn't care for, and 30 years later she creates a version of the property which is so grand and cohesive and popular that it totally subsumes the brand.
Like, for a generation or more, no matter what Hasbro tries to put out after, this group of characters is going to be what people think of when they hear "My Little Pony." They're so iconic in design and personality, their cultural impact was so large, that they totally blew all the other material that came before or since out of the water. Friendship is Magic completely replaced the property's image in the zeitgeist and has yet to be dethroned.