A lot of this should be covered in OW but isn’t.
Stressing out the marine life is not cool and leaves them open to attack. Unfortunetly I’ve had dive guides do it thinking it would make a good picture and it has cost them their tip.
That sand bottom isn’t a dessert, there are things living in the sand, one spot in the Bahamas where there was a shark feeding had everyone sit on the sand. When the sharks were not being fed it was a favorite spot for photogs to shoot Yellow jawed Gobi’s with their mouth full of eggs.
Silting up the bottom disturbs what’s living there and ruins the vis for everyone else, there is one shop I won’t travel with anymore because the owner/instructor won’t tell his newbies to stay off the bottom.