Q:

Why don't we lock voting on closed questions?

This issue came to mind since I'm facing the same in my only question; posted a long time ago. Although the question has been closed with the appropriate reasons.
But I didn't edit it further because the answer I got solved my problem.  Hence, I understand that editing in references or additional information to clarify the question is not required.
However, I've noticed that despite the question being closed, other users have kept voting it down, which has caused me to lose reputation.
This could have been averted if there was a feature which locked closed questions so that no one could vote (down or up or accept answer) on it.

A:

But I didn't edit it further because the answer I got solved my problem. Hence, I understand that editing in references or additional information to clarify the question is not required.

It might not be required for you.  It's required for us to ensure that your question is useful.  If your question is unclear, lacking a reproducible example, not accurately describing the problem, or whatever, then it inhibits others with that problem from finding your question, determining that it's about their problem, and then getting their solution.
So we want you to edit your question and fix it, even if you don't want an answer anymore.  Thus you have an incentive to fix your question (in the form of votes).  After all, closure is not designed to be permanent.  It's designed to be a state where you fix your question up so that it can be reopened.

A:

Because that would give any user with a gold badge the power to single-handedly lock the votes on a question.
That's not a good thing.
It would also prevent upvotes on questions that were actually good, but no-one ever complains about getting upvoted, any way.

A:

If we locked voting on closed questions, how would you get feedback as a question asker that your edits have improved things or not?
If your downvoted question starts to attract upvotes or at the very least cancellation of prior downvotes then you know you're now on the right track and might hope your question would be reopened.
If you don't care that your question is clear enough or that it's reopened, that's up to you but we care that questions are helpful to everyone.
If you're invested enough to take the time to write this Meta question then why not actually fix the problem and clarify your original question so it no longer attracts downvotes. In that sense voting is having the desired effect, i.e. it's stung you into action, you just now need to take the right action to fix things.

