Except undercutting has always been a thing and there's no penalty for it, so your argument really doesn't fit here.
I do think it'd be nice for us to not have yet ANOTHER gold-sink by having Earnest Money applied before the sale, since even with Elite, we still have to pay the fee, because BlueHole wants us to waste even more gold.
Of course it has always been a thing, up front broker fees ensure that it stays a thing and doesn't turn in to a problem.
Furthermore, static gold sinks are healthy for the economy and keeps item prices in check. As I'm holding the bulk of my in game wealth in items, inflation is the best thing that can happen from a capitalist greed perspective, but this is a naïve point of view that doesn't consider the health of the game, playerbase and content. Gold being inflated favors high value items which by extension favors random chance and RNG over consistency. This in turn leads to an even larger divide in wealth distribution, more players quitting due to frustration over bad luck, and more elitism and toxicity leading to more of the same - new, lesser geared players being discouraged from playing.
While I'm not directly affected by these sub-problems, and you might not be either, it will absolutely impact your overall experience when the playerbase is dead. Let's not encourage script exploits and turning the game in to a casino.
