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.
Yes, it's just misconfiguration, but when you're configuring these tools you're never thinking about the damage the autolocks do to your project if you're not very careful with the settings. Remember, the people just get turned off from contributing. They don't stick around to give feedback on this being the root cause.
Hell, I never did, and I'm very vocal about autolocking being toxic.
Even though I'm maintaining Lock Threads [1], I sometimes shake my head when I come across a closed issue that was locked by it, but I also have to admit that all I want is to ask a question quickly and get the information I need, without considering how my shortcuts affect maintainers.
There may be times when there's a legitimate reason for commenting on a long-resolved issue, but unfortunately most of the comments on closed issues are low effort support requests. Locking them as resolved is the best solution we have so far to avoid spending our time retriaging closed issues.
[1] https://probot.github.io/apps/lock/