Ironically, watching this video on Osysee results in me consuming more ads that help LTT than usual, because I don't have SponsorBlock set up for that.
YouTube creators can see the view rate for each section of the video, I'd be surprised if sponsors didn't ask for that data (if just to know the viewer retention for sponsor segments at the beginning vs end of the video)
They way I uderstand your comment, LTT is big enought so as to negotiate contracts with sponsor without being forced to share the metric related to the performance of the sponsored segment.