Today it does, yes. I’m not sure it’s been there for very long though, I’ve only very recently seen that message in the email, although granted my personal experience doesn’t count for much, maybe it’s always been there?
There’s a workaround for installing iOS apps that the developers have chosen not to allow on Macs.
Edit: I’ve just noticed that one of the steps is to send the app to another Mac and then back again (for some reason), so that might not be particularly practical.