What is the appeal from these YouTube frontends? I came to really dislike them because links are broken after a while because these sites don't live very long and the video data itself is still streamed by YouTube? I don't get it.
In case of piped and freetube you can subscribe to channels without Google account (freetube does that even offline), it's also possible to import channel subscriptions from Youtube.
There were instances that shortly existed, or which tried to redirect you to some suspicious sites but these were filtered out.
Some of us feel supporting Google in any way is unethical, but still want to consume some of the content they have lured people to put on their servers.
Also, most of what I watch on YouTube is clearly pirated (or ad free). That’s pretty much been their business model since day one, though they have diversified a little into legitimate for-profit content that is supported by ads.
If everyone blocked ads content creators would be forced to research platforms that allow direct payment via micro-transactions, merch, or direct donations instead of ads. LBRY and liberapay exist.
If creators want me to tip them, they need to offer me an ethical to do so with money. I will not pay adtech companies with my time, or money, ever.
If you only care about the channels you’re subscribed to, it’s a much better experience.
A tremendous advantage to viewing without authenticating is that you can quickly set a strong affinity based on your current interests, and don't have to live with consequences of viewing low-quality content for hours, days, months, years, millennia, etc.
If Invidious and Piped offer(ed) the option to permabam channels as well (to those subscribing directly to those services, or even within a single session), so much the better.
Videos can also be optionally proxied in some instances but that wasn't a draw for me.
It's up to the instance admin for Invidious and the behaviour of Piped to proxy googlevideo. Not sure if it's visible at Invidious if you use an instance that doesn't proxy the traffic, but you can be sure it's proxied when you use Piped.