We did this with Opera Mini. I think it could have worked, sorta, if we had staffed this properly (meaning 50/50 on tech support/development. we weren't in a position to do that). But only early on. The early users were kinda techie (beta users were great! smart people who could speak english!), so it worked decently well until we reached like 1M MAUs. At 250M MAUs it was just random noise to a human. And the volume was insane.

It didn't help that were all Swedes and the vast majority of the users were Russian/Indonesian/Nigerian/Indian. Language-specific ML could definitely have helped nowadays, but this was 2005.

Another aspect:

The content was so "inappropriate" that we felt that we coulnd't really recruit young/cheap people with the proper language skills to watch these feedback channels. It just felt.. well, wrong.

Here's a lesson: if you build a browser and target it to people who have not been exposed to the Internet before, most users will use it to access porn. Not wikipedia.org, un.org etc. Very, very hard-core porn.

(We did notice that they actually started looking for things besides porn after a couple of years, though! I guess it's something people have to go through...)

Which they do. There is absolutely a report bug item in the help menu. There's a full "Feedback" section in the menu made exactly for this purpose.

... and then deal with several thousand bug reports a day? as much as I'd like that from a user perspective, a bug report is only helpful if somebody will actually take a look at it.