1. Removing entire series/movies
2. Removing specific episodes in a series
3. Making changes to content (e.g. Scrubs and its soundtrack)
4. Only having the inferior quality version of some content
5. And finally, to a lesser extent, just having bad metadata (Netflix in particular has listed episodes out of order)
I'm becoming more and more envious of those YouTubers with the wall of physical blurays and games as their backdrop.