Ah, you are touching upon a slightly separate aspect, which is just the quality of trending itself. I remember arguing in the past that the way we would actually achieve the quality is by actively downvoting, and I can't find links now but plenty of people have argued for doing so. If enough stake is used to downvote trending, it will clean up trending, and would have the effects you are talking about. And funny enough, re: fight fire with fire, check out @bid.bot which amuses me very much.
The other part I'll touch on is that the trending page is an advertisement to the steemit world too, which is why plenty of people are taking initial losses to gain a lot of attention on trending.
I don't think using stake for promotion in the form of bid bot economy is the right way to do promotion. It shouldn't take anything from the reward pool. Trending is owned by the platform, not by bid bots, they simply took control of it because no other promotion form exists. And the other aspect of that is that the payout values don't mean anything with bid bots. It's just a mess. One way I saw that is interesting to me, and would address the concern about taking from the reward pool is what @freebornangel is suggesting in their comment, which is that all bid bots simply should focus on the promotional aspect and require all posts to be declining rewards. The problem is... well, fat chance getting any of them to budge.