>>40425983NTA but the short answer is everything. FiM happened in the short period after Internet started becoming popular, but right before it became a playground for corporations. In 2023, 95% of internet users are safely locked in their little content bubbles where algorithms show them the content that the corporations want them to see. A natural hostile takeover of the whole internet (like what ponies did in 2011/2012) is completely impossible by design.
The other big thing is that the mentality of internet users shifted. People are eager to check out new "fandoms" then leave them after a month or two when the bandwagon drives them elsewhere. These long-lasting fandoms like Trekkies, sonicfags, etc. are a thing of the past. Internet moves at least ten times faster these days. FiM also somehow lucked out there, catching the tail end of that previous era. Such long term commitments to anything aren't cool or popular any more.
tl;dr: Internet is now built to not allow it, and people wouldn't be interested anyway
