The metrics aren't the same
The community isn't the same
The value isn't the same
There's no 1:1 comparison with platform social media and I think we do ourselves a disservice by looking at legacy metrics as the most important. That doesn't mean they cant be useful in some ways, but I think we should recognize just how much noise there is in a typical network that makes a useful comparison extremely difficult.
Especially when what you get out of it, how likely your followers are to see your content, and the level of connection to the community can vary so greatly.