What if there was a minimum character-limit? That would immediately help filter out these low-effort message senders, wouldn’t it? And the expectation, as far as it seems to me, is usually to say something about yourself and your trip in your introduction message when trying to find a host, anyway.
Although I suppose that could easily be bypassed by these same people just making one longer message template and copy-pasting… but I would bet fewer people would put in that effort than the amount who just throw random “Hi’s” around.
And to answer, as a male, I definitely have never been flooded with inane messages. I don’t think I’ve ever received an opening message that wasn’t descriptive and intentional 