Every question should get a response, even if it’s a response the member won’t like.
No, they might not be able to integrate your tool with a specific service.
They won’t like that answer, but at least now they know.
They know not to keep searching for the answer, call customer service, or struggle to do something which can’t be achieved (and getting angrier).
Yes, there might be a legal reason why you can’t respond to the question. Far better to tell them (that exact sentence) rather than let the comment go unanswered.
If you don’t get a good, quick, response you won’t use the community again.
And if you see most discussions don’t get a good response, you won’t even bother asking the question.
If someone takes the time to ask a question, you owe it to them to make sure they get a response.