This is why OSS looks like a cult at times. People are allowed to criticize your project and complain about it. They have no obligation to become a contributor. "Submit a PR" is such a conversation killer.
A PR needs maintainer approval. And the maintainer I've seen thinks the documents are good enough already. In cases like that, a PR might not be able to solve the problem.
Complaining about it reroutes people to better projects, and pushes the project to fix the problem.
I didn't use try Traefik's documentation, but the complains appear to be somewhat structural. Meaning a PR would need to possibly restructure at least part of the documentation, or add a whole section of documentation of a different type.
You can't expect someone not core to a project to just propose to restructure the whole documentation. Which may also mean changing the website.
And in any case, such overhaul coming from a "nobody" would very likely be rejected as being both too large or incomplete or not desirable.
Re-structuring needs to be pushed for by at least one person from the core team.
So yeah "Just submit a PR" in that context is not an answer, it's an excuse to avoid trying to understand the problem and actually improve the situation.
Customer: I can't find anything I'm looking for in your store.
Store: I spent a lot of time arranging things around in the store, if you can't find what you're looking for you can stop complaining and write signs for us.
Customer: Or I can just use your competitor who actually cares about their customers. ¯\_(ツ)_/¯
The relationship around this is open source, users and alternatives. It may not be money but nobody writes open source for the github stars, they want users and if your users are frustrated they'll go to alternatives.
