because decentralized systems need to redundantly store data, a lot. Youtube accounts for, depending on the source 15% of global internet traffic.

The reason you can watch videos at 1080p wherever you are in the world buffer free is because the system is ridiculously optimized, cached locally, and so on. Do you want to go back to 180p because one of the two guys hosting that five year old video with 50k views you liked just went offline?