There’s no special reason maintainers have to respond to (or even read) every comment on some years-old issue. If maintainers have their email set up to pester

There’s no special reason maintainers have to respond to (or even read) every comment on some years-old issue. If maintainers have their email set up to pester them every time someone writes a comment anywhere, that’s the fault of the email setup, not the commenters’ fault. Instead of locking the topic, consider just leaving a note that future discussion there is likely to be ignored by the team, and then letting users continue to discuss workarounds, etc.; often the issue tracker is the only kind of discussion/help forum available to project users.