I think its just important that one has some close friends in different or similar levels of connection. ie: Sports friends, reading friends, social friends, etc.
I have to admit - at times being alone isn't very healthy. Also being with people and still feeling being along isn't healthy either.
But still having someone that can hold you and listen to what you say and communicate does make life a bit better and returning the favor also helps to promote good relations. I guess its to ones choosing to how close one should be. No sex to Casual Sex to Full Sex. Understand that we human and we're bit animal. So communication is done in more than words but tactile and must be done with mutual understanding to never harm nor violate the trust.
Now if Promiscuity leads to unfaithfulness, less devotion, etc of the evils then what you say is very much warranted. But if its for your own excuse to being alone then I guess the excuse has gone too far.
Now if it leads to finding that life time partner or that true close friend(s) and then the search is done for awhile then there's no harm done.
Doing things that you're not ready for - or - rather too young to take on the responsibility should be avoided until you are.