Meta has several of the biggest UGC platforms, and in this case the complement is content itself. Reels with autogenerated (and royalty free) background music is the obvious example but I'm sure there are more. Maybe creative for ads as well?

In short term it's social media, because people will share whatever they generate on social media. But I don't think it's a very strong incentive to invest in AI for Meta.

Content is a complement to social media.

To Metaverse access. Filling the metaverse with engaging interactive 3D content is an insane job with 2020 technology. It requires a huge amount of a range of skilled labor to create 3D models, soundtracks, NPC dialog, visuals et.c. to make a compelling experience. In 2030 that may have been reduced to that everyone with creativity and Internet access can do it. Sure, most of it will be silly things - but so is social media today, does not make it any less of a commercial success. And there will be be millions of semi-pro creators to create the things with higher production value, like with videography today.