I agree with GP that you don't need to answer anything you don't want to, and ignoring is a valid approach. And I think closing issues is also a valid approach, it's your project after all and you can do what you want. That said, I would prefer maintainers didn't close issues that aren't actually resolved, and instead just ignored them. Maybe apply a label like "Needs more info" or "too busy to investigate" or "help needed" and just filter them out of your view.
The reason for this is that it allows others to chime in and add to the issue, and for users to discuss it among themselves and even find solutions and workarounds. I can't say how many times I've had an issue with some open source project and I find related thread in the github issues. And often the solutions or workarounds are suggested by community members, not the maintainers. But I find it soooo frustrating when the issue has been closed by a "stale bot" because it hasn't been active for 30 days.
This is the spirit of open source, IMO. The creator shares their work with the world, with no commitment or obligation, and the world makes of it what they can. Maybe the maintainer volunteers to help people troubleshoot their issues, or maybe the maintainer is too busy. That's ok. Let the issue sit there, and maybe another kind soul will happen across the issue and answer the question. There isn't enough info to reproduce? That's fine, it's quite possible - even likely - that someone else experiencing the same problem will find the issue and be able to add more context.