Most of the other uses are pointless.

I don't need WebRTC for chat, because IRC is still working just fine.

I don't need WebRTC for video calls, because Skype is still working just fine.

I don't need WebRTC and WebAssembly for online gaming, because I have Steam to install games locally. Plus latency and performance of games emscripten-ed to wasm tends to be atrocious.

So the only uses where I have seen the new Web* APIs in my life was obnoxious ads and newspaper websites trying to shove recommendations and notifications into my face.

What would you want to cross-compile that couldn't be done much better by building a proper local app?

Plenty of downvotes, but no productive suggestion of what use-case would be best served with WebRTC ...

WebRTC enables many of these things on the browser. That is the point. So your "I don't need WebRTC because I use native apps" is basically just "I don't need the internet because I can go next door to talk to my neighbors".

Just because something doesn't have value for you does not suggest it does not have value, period.

Almost. I'd say my argument is "I don't care about an online egg retailer shipping from China, because using the local supermarket is better in every way."

And obviously, Skype and IRC use the internet, too. So what is the benefit to me - the user - of "Skype inside web browser" over "Skype separate of web browser"?

I understand that WebRTC makes "Skype inside web browser" possible, but it also makes a lot of less desirable behavior possible. So there is be a trade-off between the advantages and the risks from adding WebRTC.

Which benefit does WebRTC generate for the user? I.e. why is it a good thing that web browsers added this?

That's just a matter of browser software. The Web platform should not suffer just because the browser is imperfect. You can write your perfect browser, fairly easily with the libraries available. I will try when I have some time.