Pixiv, Fanbox, DeviantArt, Tumblr, etc, are also widely used. Very few people only use a single platform. I think Twitter is top 1 for expanding your audience not only because how well their feed algorithm works, but maybe also because all those focused platforms are used more by artists and less by viewers (or used less often by viewers), while Twitter being general-purpose is the one where more people who like to watch/discover arts but are not artists themselves, are. But there are other factors, like Twitter comments being better than Pixiv or DeviantArt comments, etc. Finally, if we return to the context of this discussion, I don’t think any of those dedicated platforms in any way solve the problem of age verification and that is why I wouldn’t recommend migrating to them in this context even if they were otherwise good for art.
Pixiv, Fanbox, DeviantArt, Tumblr, etc, are also widely used. Very few people only use a single platform. I think Twitter is top 1 for expanding your audience not only because how well their feed algorithm works, but maybe also because all those focused platforms are used more by artists and less by viewers (or used less often by viewers), while Twitter being general-purpose is the one where more people who like to watch/discover arts but are not artists themselves, are. But there are other factors, like Twitter comments being better than Pixiv or DeviantArt comments, etc. Finally, if we return to the context of this discussion, I don’t think any of those dedicated platforms in any way solve the problem of age verification and that is why I wouldn’t recommend migrating to them in this context even if they were otherwise good for art.