MCU: Why Netflix's Marvel Experiment Failed
2. People Felt Like They Needed To Watch Everything (So Watched Nothing)
Another aspect of the shared universe that ultimately hindered each series was just how essential Netflix and Marvel wanted everything to feel. They didn't just want people to watch The Defenders, they wanted subscribers to view Daredevil, Jessica Jones, Luke Cage, and Iron Fist, and then come back for seconds and even third helpings.
While most of the shows, especially post-Defenders, do largely standalone, the damage was already done. If you missed one series or fell a couple behind, which is easy to do when Netflix alone have so much content and there are many others 'must watch' series elsewhere too, then there was a sense of being unable to catch-up, and so just not bothering. The movies have had this problem to a degree, but there it's easier because it only requires two hours of investment for each instalment, rather than 13. With so much required viewing, it's not much of a surprise people started giving up.