Yes, it certainly was excessive, and as you said above, out of control. I certainly would be bothered about it! I don't think the remedy is making up "nice" signs, inconsiderate people like them will not pay any attention to it and you will only get more frustrated.
Clear rules are best.... and by all means, don't lead anybody into temptation by even having more towels accessible.
I have an extra linen/towel closet I point to where my guests can take more if they need to, but the extra supply is limited! and like a lot of other hosts said here, usually people Re very considerate re the use of towels. I would write it off as an abnormality. But it also seems to be true that the more people are in a rental space, the more potential trouble ensues.