I guess it’s a case of “why not”. I’m sure someone could make a client that does the same thing but there’s a few features of mastodon that are geared towards text content rather than just images (quote posts). Likewise there’s probably some features that make sense for an image first platform that probably aren’t needed for mastodon (showing camera setting used).

Hopefully federation between the two does improve to the point that you maybe couldn’t tell at first glance of a profile is on one or the other.