They don't need more games (although it may work once), they need more keys for the most wanted games and to disable the direct server protocols they allowed the time the button vanished on normal users.
If they were doing bot prevention by game listing it would possibly slow down any bot checking prices but with multithreaded apps as simple as multiple batch files these days its not going to help much...what would have screwed up any bots not doing thorough checks would have been to list them in random order and price some fools gold "your automated and you bought nothing but being banned" button at the highest or second highest cost each month
They could impliment multiple methods for banning beyond checking user by user like that concept...nobody is buying a ban button if they're looking (and if they did too bad lmao) just retrieve the ban logo as a mixed png image from the server side so nobody coulld read it and add it twenty minutes before the vault opens.
Being technically elite doesn't make a good programmer, ingenuity and thinking outside the box is a far more handy characteristic.