Sponsorblock only works on specific, known timed segments.
That's not true though, sponsorblock is user reported, that's why it works for sponsor segments and in-video ads of all lengths and locations in videos. If ads get baked into a video they can't be taken out or changed, since that's what getting "baked in" means in this context, and as soon as a single user reports the ad it will be blocked by sponsorblock for anyone who uses it. If it can be taken out or changed, then it's not truly baked in and that can be exploited.
If they make it in any way removable no matter which end its on then other people will be able to figure out how to remove it too.