Just out of curiosity, how many of you have a red dot or some other optic and have NO flip up/back up/offset/iron sights?

Or, how many of you just have a front sight?

I know this sounds like a stupid question but I have noticed a lot of setups that have no sights other than a red dot or holographic sight. I have seen a lot of youtube videos where SF guys have a micro T-1, comp m4s, eotech and no BUIS at all? Thought it was worth asking. I understand that sometimes a rear flip up wont fit with a particular optic or wont allow you to place an optic where you need it.

Just asking, if not, what is your reason?