There are two reasons why P2P has been generally less successful than a lot of us hoped around the turn of the century: the first is largely technical, namely the small number of people with plenty of uplink bandwidth, and something like municipal fiber would actually help a lot there. When people have 1,000/25 connections they have less capacity to share in general and with things like video chat and gaming being common, the amount of idle capacity consistently available is relatively limited.
The other is harder: some ISPs outright blocked or throttled P2P protocols entirely (much to the annoyance of, say, Linux users torrenting ISOs) and most others will have some mechanism to respond to copyright claims. The latter is really hard for a YouTube competitor if it allows anyone to upload content — if the network attempts to auto-mirror content, you are potentially at risk if someone uploads something illegal; if it doesn't, only the most popular public content will be well-replicated.
Unfortunately that all seems to be proprietary money making territory right now.