The functions to DM and Follow people are still there as far as I can see.
In my case?
Yes, of course they are, because I haven't actually - as yet - set boundaries on them. That doesn't mean that this will always be the case, or that I will always choose to leave the settings (boundaries) as they are at present.
However, I welcome - fervently, passionately, and whole-heartedly welcome, approve and applaud the fact that I
can set such boundaries should I choose, or wish, to do so at some stage in the future.
One of those boundaries - for the record - allows you to 'block' someone; that means that the individual blocked cannot see your posts, and - most certainly - cannot DM you.
As
@rm5 says, - and I agree completely with him - "Someone can contribute to a community without you knowing every single bit of info about them."
Besides, it is not "useless", because it allows you - or one, or the individual in question - to set boundaries; thus, this gives the individual the right - the autonomy - to determine just what they are comfortable with others being able to see.
Therefore, depending on circumstances, or mood, or personal choice, or personal preferences, one can change what one wishes others to be able to view, or see, and yes, one can still make posts.
The more I look at this and the more I become convinced that people thinks it does a lot of things, but it actually does none.
It can do a lot of things should people wish to enable those functions; this is a matter of personal choice and preference on the part of the individual member who gets to choose where to set their own boundaries.
Thus, they may enable these specific functions, they may enable some of them, they may choose not to do so.
You get to set your own boundaries.