I would not do it; keep the question focused on the problem rather than the software. A better answer from a different platform can come in the future.
Otherwise, we will flood the system with similar questions, when we could have few posts with a full repository on a problem or task. It is ok to ask about a specific software, but the demand should come from the OP, not from the community trying to fit every question to a software.
An accepted answer on such questions means that an alternative solved the OP's problem, but it is not describing the question demanded software 'x'.
Found the below related post:
Should I add a tag to a question, if it's associated with the marked answer?
by Bill the Lizard:
In general, it depends. Would adding the tag exclude other possible answers that don't include the subject of the tag? If so, then don't add it.
I think this is the case here. Labeling a question with software 'x' when the OP clearly did not demand software 'x', will exclude other possible solutions with software 'y', 'z', etc.