A brilliant move would be to offer discounts on purchasing a game if the lender kicks you off while you are playing. "Sorry we have to kick you off while you are playing, it looks like the owner wants to play game X right now. Purchase the game for yourself at 10% off and keep playing immediately!"
so a 10% markup on everything, which people have to circumvent by intentionally trying to play the game at the same time just in order to get the 'discount'?
Because Steam sales have driven the prices of games up by 50%. Oh wait, no, AAA games are still $60, but now Steam offers them at a reasonable discount after a few months to undercut the used-games market.
Getting kicked out is a point of friction, where a user could either start torrenting, or buy the game legitimately. If they can prove that a small discount improves conversions, I don't see why they wouldn't offer it. Steam is all about removing friction by offering discounts.
Define "slimy". Offering someone something which you have a very good reason to think they'd want seems like about the best that marketing can ever be.
There's lots of slimy marketing tactics. Here's one.
Give someone something for free, without telling them its a trial, then have it break down in some predictable manner shortly, then sell them something very expensive to fix it.
Example. You buy a printer for really cheap, you're happy with your purchase, you print off some pages and then after the 8th page, your printer runs out of ink. You go back to the store to see ink for your printer is exorbitantly marked up.
That is a slimy marketing tactic. It relies on common weaknesses in reasoning we humans have, in this case, a sunk cost. You've invested time and money badly, and you are unwilling to see what lies ahead as a worse option as backing out and getting something else.
Can you see parallels with this tactic in what steam is doing?