There are services that incorporate P2P (e.g., Spotify, and you can find others if you do some research). If you're writing closed-source software that operates on content that belongs to you (or that you've legally licensed) there's nothing preventing you from using peer-to-peer technologies in your stuff.

I can't believe that Netflix didn't seriously consider P2P. I imagine they didn't do it because there are issues with consuming limited upload bandwidth that doesn't belong to NF, and having poor control over the resulting complicated network flows and the ultimate customer experience (think about what your first customer service action for a customer having video quality issues would be).

No doubt there are many managers and system engineers who shy away from P2P because it's associated with bad actors. But there are sound reliability engineering and customer-facing reasons not to use it, too.