We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember "Farouq"
saying something like:

I am considering spray painting some rooms instead of using a roller
and brush. It seems to be so much easier than spending ages with a
roller and brush.

Why is spray painting not popular? are there any disadvantages that
I've overlooked?

I know there is the original cost of buying the equipment which makes
it more expensive initially. After that it should be much easier to
paint the room?

HighVolumeLowPressure is the way to go if you're intent on doing it.
Fwiw, I've painted indoors with the HVLP system and it works well. You
don't get much overspray and the paint is quite controllable.
--

Dave