Have you ever clicked on an interesting account on Mastodon but it was empty, with hardly any posts or followers?
It might be that the account is very active, but your instance just hasn't updated its data about it yet because it's on another instance.
To see the latest info about an account, click on its profile picture to open its public page. This is hosted on its home instance, so it's up to date.
For example, switching.social's public page is https://mastodon.at/@switchingsocial