If the site tries really hard, they can control serverside how many seconds of ad you watched to decide if you can access any content whatsoever. Something like this is already present on Twitch iirc. So in the endgame the only universal detection-proof solution I can imagine is AI/GPU based adblocker that will visually detect ads on your screen and overwrite them with something else without actually skipping.
Do they lose their karma after deleting the post?