The viewing-is-sharing model is indeed a problem of PeerTube - and, I'd argue, of any decentralized network based on a P2P mesh. But it definitely alleviates the content distribution asymmetry problem - by spreading the load on the viewers small/medium instances can afford to scale up much more easily.

You can alleviate the problem by browsing some "borderline" profiles/instances with Tor/VPN though, or even just disable the "Help share videos being played" setting from the profile settings.