Currently, there are a lot of old SO-specific meta questions laying around on this site, asked back when this site used to accept them, before the MSO-MSE split. While many of these have been closed accordingly, quite a bit are still open, and I'll gladly vote to close one if pointed out to me.
On this site, users are limited to 24 close votes per day. (It was increased to 50 as a result of a big wave of off-topic questions; to be fair, I'm to blame for letting them know a long time later that they forgot to change it back and they did so per my request.)
Our Close Votes queue generally only gets 0-5 questions per day. This leaves people with the ability to vote to close other questions as they please without running into limits, and allows users to deal with things like blatantly off-topic questions, hammering duplicates, etc. There are generally only a few users (~10-20) who do that on a daily basis on this site.
But occasionally, the close votes queue gets filled up with dozens of these old SO-specific questions. Users without enough rep to vote to close can flag questions for closure, and if they have a long history of good flagging, they can add up to 100 questions to the queue per day. On this site, I had raised 400 helpful flags, mostly recommend closure flags, enabling me to cast 50 flags a day, before I gained enough rep to vote to close. On Stack Overflow and Super User, I can cast 100 flags per day despite not having enough rep to vote to close.
As I said, I don't disagree with those flags; I think it's great that the user(s) who is/are flagging those questions is bringing them up to our attention, so that they can be closed. But the daily close vote limit can leave us few users who deal with them daily with very little power, after we've spent some time handling those review tasks. After taking care of the queue yesterday, I came across two blatantly off-topic questions that I was unable to vote to close, and judging from the low amount of close votes after some time (they generally get closed very quickly), I guess many others also had the same problem.
What should be done about this? Should users without closing privileges be limited to casting 24 recommend closure flags per day, limiting them to adding only the same amount of questions that a 3k+ user can add to the Close Votes queue? Should we raise the daily close vote limit to 50 on this site? Some more complicated solutions are to increase the daily close vote limit in case the queue gets filled above a certain threshold on a given day, or to make close votes cast through review not affect the daily close vote allowance. (These seem like generalized solutions to localized problems, since this issue reported here is specific to MSE.)
Also, another thing: if the queue size goes over 150, the daily review limit gets increased to 40. This can happen if 2-3 users with great flagging histories flag a bunch of these old questions. But that doesn't make mathematical sense if I can only vote to close 24 of them, and that can leave my close votes altogether depleted.
To be clear, the issue at hand here is about users who vote or flag many of those old questions that don't have an immediate need to be closed, and are very likely doing so in the name of cleanup, per Nathan's answer below.
For now, I'm going to tap Leave Open on old SO-specific questions that have no close votes and have no recent activity; others please join me in doing the same so that flags get declined and the user(s) who floods the queue will get the message.