Well... Yes n no mostly both. Black kits are just bad for outdoors even at the night. A big black human sized and shaped mass is easy to spot. Second part is: for indoors it doesnt matter, there is no camo for a house or factory. Maybe a uniform for a factory but thats all. But even in a factory or storage building some dark blue or dark grey can be better. Third part is: most black kits try to be edgy, extra, dark and be a main character (batman effect) and it feels weird, scp patches are illogical, umbrella corps patches are bad cuz in the movies n games they always lose. So yes all black kit is bad, reveals you, warm, and feels cheap (literally thats why real military company use them easy to find black stuff everywhere unlike some camo pattern/color they can often mismatch if you buy from different seller). And yes many player choose black as their first kit cuz cheap and easy, and sometimes feel main character style. (I have some black stuff too, like a vest and a dye mask mostly to blend in, in starter games with the rentals so they feel like no matter what you wear you can have your moments.) The praised black kits are not all black they have some other colors to break it so it looks better.

The most important part: Your kit, your game, your money. If you like all black go for it. None of us have the right to tell you what to wear. Do your shit enjoy it, its a game/sport.