There is nothing particularly shady about the setup with Vitesse. Lots of big clubs all over Europe have formal or informal agreements with smaller clubs to loan players and exchange information and resources. Vitesse are compensated both with the talented players they get from Chelsea, and also in the form of straight cash. Manchester United used to have a deal with Royal Antwerp in Belgium where they would stash players who didn’t have a work permit.
One could argue the merits of the loan system in general, but there is nothing overly suspicious going on in Chelsea’s case, other than them having a larger crop of loaned players compared with most clubs.