I've been on Upwork for about 2-3 weeks now and I've got 27 active proposals, most of which are almost 10+ days old, and I haven't heard back from the clients... is it wrong to revoke them and mark them as unresponsive?
It is not "wrong" to revoke your job proposals.
It is not against the rules to do so.
It is not unethical or immoral to do so.
If you want to revoke a job proposal, then go ahead and do so.
However, I can tell you that the advice commonly given by experienced freelancers is that there is no reason to do so, and it might be best to NOT do so.
The question to ask yourself is this:
What do I gain by rescinding a job proposal?
Answer: Probably nothing.
But what if do NOT rescind a proposal? Is there anything to gain?
Yes, there MIGHT be.
If you send a job proposal, and that job is taken down by Upwork because it violates Upwork ToS, then you will AUTOMATICALLY receive your connects back (if you didn't withdraw your proposal).
If you send a job proposal, and that job NEVER hires anybody and then closes, then all of the freelancers who submitted proposals may get their connects back (IF they didn't withdraw their proposal).
Also, SOMETIMES clients simply take a long time to hire. Sometimes a freelancer submits a proposal, and doesn't hear from a client, but then gets an invitation to interview or work on the job a week later, or two weeks later, or a month later (!). I'm not saying to count on it, but it DOES happen. If you withdraw your proposal, that can't happen.