Eh... All the data is already with meta through Instagram, it's users is the target here. I'm sure most of Instagram users aren't complaining that much about collection of data. As long as this kills twitter I'm happy. Who knows it might point the rest of the users towards eventual decentralisation.
You probably found a bunch of people with niche (if any) interests and/or friends from Twitter or other social media who are active enough for your feed to be populated. A lot of people use twitter to follow news, celebrities, journalists and shitposting accounts with large following as there's lots of discussions under tweets with massive reach. Most people don't interact themselves at all but just scroll. Mastodon doesn't have these big accounts as of now so there's not much activity for the majority of regular twitter users.
WhatsApp, YouTube, Spotify
wefwef is the smoothest right now and it's just a webapp
thispersondoesnotexist.com has been around since 2019