De-anonymisation for one.

But more generally, if I’m the sort of person who would allow this I’d probably allow some other stupid permissions if they promised me something novel on the other side.

Well they have your IP....and browser fingerprints....rough time of day if a window, direction, weather....products you bought....your age...possibly health issues that come up....essentially any information that can be used to schedule and stalk you...

You are giving your face away, for one very obvious point.

Never give a random website access to your webcam. This is basic privacy 101.

I'd love if the people who put a tape over their laptop webcam could answer this.

I can potentially know if you're home or not and then rob the fuck out of you or kidnap your family members, for one.

Palmprint?