receiving is not really worth it (your shader likely generates 'fake' shadow effects based on light direction regardless!), most people don't use it so it's a bit uh.. i guess inconsistent with other people's avatars.

it can be useful on some shaders like toonlit for quest, though it doesn't look great, it's one of the only ways to get shadows on quest avatars. that being said, you're still affected by light/darkness so it can be skipped there too.

also if this helps convince you to keep it disabled, your shader probably does msaa without taking into account shadows. you end up with a halo of pixels around anything significantly darkened by shadows. i used to have a screenshot of this in vrchat, but here's one from the net instead. this happens with the vrchat mobile toonlit and im sure others too.