Haven't watched a single YT ad in years. Leeching is not good for the creator but then neither is the length of time wasted in a video for ads and self-promotions and time has far more value for me.
At the same time, I don't watch videos from every Tom, Dick and Harry who turn up in the recommendation list or try to self promote through blogs and forums with subscription mostly limited to media houses. Considering how YT has led a lot of people into a rabbit hole, can't say it has been generally for the good.
A good compromise would be to have in-video promotions without detracting from the main topic which actually Google doesn't allow since they want their own pound of flesh. However, considering how movies and music have survived piracy, I am pretty sure the vast majority of viewers have no idea about any of these apps, so I guess in a way we can be thankful to them.