... it tends to filter out the actual bugs from the situations that are more a question of user understanding and education.
Though some of those misunderstandings and some of that need for education could perhaps reasonably be considered shortcomings of the software.
I my time as a developer I had actively to encourage our sales and support people to feed information back to us. "I don't care if the customer 'gets it wrong' or just feels it isn't righ ... I'd like to know about it. We may address it, we may not, but if we don't see the message we'll do nothing."
We set up a system deliberately
not called a bug/fault report and actively encouraged any feedback they liked. And they did.
Most was also sensible and constructive.
One of the things that does is pick up bugs/faults/quirks that the more experienced users never see because "they never do that"; Sometimes there were good ideas that previously wouldn't have come to us. PGM's wishlists help with that.
Actually, later we also had a couple or so meetings each year with the sales and support guys, where we all just talked about the system. Sometimes things came out in those meetings that people thought were "just silly", that were actually useful to know.
I don't see how any vendor could have a public bug tracking system that wasn't vulnerable to inappropriate entries...
You're right that a free-for-all would be a bad idea, but it would be nice to have an opportunity to see what's been recorded, what if anything is being done about it, what version contains any fix, and/or where the workaround and/or misunderstanding/education data can be found.