I worry about the perverse incentives point, but I also get so overwhelmed by all the books I’m reading at once that it gets counterproductive, and I never finish them. I’ve got… I think six on the go at the moment, which is actually not as bad as it has been (coughthirtycough) but it’s enough that some are definitely being neglected.
(I do have an incentive system for that – I’ve gameified my reading list so I get a certain amount of points based on the length of a book, how long I’ve owned it, how long it took to read it, etc. It mostly works, hence not having thirty books on my currently reading stack, buuuut…)