9 out of 10 "new old stock" chips on sites like Alibaba are harvested from ewaste. The "recycling" process generally involves workers holding old circuit boards over open fires to melt the solder, and then banging the boards against the ground to knock the chips out. After that, the recyclers sand off the old chip markings, cover the tops of the chips with a tar-like material, and laser on new chip markings (this makes sure that when you buy 100 chips from a seller, they all have the same markings and date code). Since they're applying new markings, they can also take the liberty of making the chips into more expensive versions, such as by increasing the rated clock speed or by labeling consumer versions of chips as milspec or radiation hardened versions. This may be fine if you just want an old chip for a hobby project or something, but for repairing military equipment you want chips with a verifiable chain of custody.

Because military.

I doubt there's actual 8088s being used in consumer products; it's mostly military (and someone else mentioned avionics in another comment here) applications that require exact qualified parts, and can't be replaced with something else. Alibaba's are probably recycled or NOS.

In military/aerospace you're mostly paying for the paperwork, not anything physical.