This, but unironically. Games don’t even need such realistic graphics, anyway - I’d much rather play a stylized or even 2d game where the devs focused on mechanics and fun, rather than pretty lights.
Hollow Knight, Crosscode, Hades, Dead Cells, Signalis, Dusk, Outer Wilds, Underrail, and more are all great examples of relatively modern games that kill it in the graphical department without using anything fancy.
Celeste still has really nice lighting in places, imo, but you are right, it all just comes from good colour choice and artistic skill, not some premade graphics option that they flipped on.