I'm afraid I don't agree. I recently went on vacation with more than 50 trackable items to put out, and came home with only 9 found. Out of 60 caches that were shown to have trackables, only 6 had any, and only 1 had more than a couple (and that one had the rule posted on its page, and in the cache ... TAKE A BUG, LEAVE A BUG). Overall, it was extremely disappointing. I'd looked forward to having loads of cool new things to discover and pass along.
I kept wondering, 'where have all the trackables gone??!!" Well, in one local instance, I know. A new cache was published, with 25 or 30 trackables to start it out. The third person to find it took them all and left nothing in their place (a notorious area hoarder), so the fourth person found nothing.
I realize that not everyone has trackables to swap, but finding empty cache after empty cache can be very dispiriting. I did my part by leaving 1 or mroe trackables in nearly every cache with space ... and most of them have already been picked up and moved on, so apparently I'm not the only one who likes to find them.
Personally, I'd much rather find a beautiful coin, or fun travel bug, than a packet of salt, some cotton swabs, or loose buttons.