You also have the issue that you might be dropping new requests, but there's so much backlog that old requests eventually time out in droves, too. You might end up spending a lot of CPU cycles doing partial work on some requests, only to eventually see them hit their deadline.
That's one of the reasons why Facebook has a mechanism that switches their FIFO queues to LIFO, once the server has passed a certain load/latency threshold.
But mashing reload is what users are supposed to do by design of the web.
That is, errors in internetworked systems can happen at a level high enough that machines can't decide if it is sane to retry or not, they should simply bubble the error all the way back to the user and let her press F5 if she wants to.
Modern UIs might hide this, but users well know the web is flaky and understand it in their bones. So when they press reload they are sending important information.
That's one of the reasons why Facebook has a mechanism that switches their FIFO queues to LIFO, once the server has passed a certain load/latency threshold.