It isn't p2p, there are servers hosting the par2 files, which are fragments of the file you want. You are paying those servers for access to those files. Also you'll be paying for the indexer to tell you where to find them.

Everything has its pros and cons.

The big pro is if the file you want is there, no waiting for a seeder with a terrible upload. You will get it as fast as your VPN can take you. I often see 40 down.

The big con is they are a centralized server so they have to respect takedown notices. This is less of an issue than you might suspect.