Everyone in the world who has imported ThomasV's PGP key (assuming his email is verified), can retrieve the key from a keyserver, attempt to verify your binary, and notice that it fails because of wrong signature.
So the keyserver plays a very important role (I just wish GPG shipped with a default keyserver that actually works!

)
Depending on a keyserver again means depending on a centralized entity, which is what aliashraf is trying to avoid.
Except if you define 'people have a local copy of it' as
decentralized, which is how I called Git's current state (
'somewhat decentralized' as in: anyone that has a copy of the bitcoin/bitcoin repo can push it to a new remote if GitHub remote server goes down).