Well, if every small house sale pulled 40,000,000 out of the economy, each NA world would have been sunk an average of 31.6 billion gil in the past year. That's not even counting the considerable added value of mediums and larges.
(My math is 19,000 house purchases in NA during 2020* divided by 24 worlds equals roughly 790 purchases per world at 40,000,000 each)
Well, prior to the timer it was popular to purchase a house for 3m and then offer to relinquish for 20m+ to a prospective buyer. That is no longer possible at all, so in that way the timer did stop it.
My proposed change would bring houses closer to what people are willing to pay for them, and hopefully make the timer unnecessary. I honestly don't think even a handful of people would pay 84 million gil for a small house, and certainly no one is paying 315m for a medium (I mean, maybe for the medium). Keep in mind this is for resellers who want to make a modest 10% profit, not the ridiculous gouging that occurs presently.
40 minus 40 is 0. No one is going to do business just to break even. Right now you can spend 3m for a house and sell for 40m, 1300% profit. Spending 40, you'd have to sell your small FC for 520 million to make the same profit. With placard cost brought in line with demand, it's far more likely for the FC to come upon a house available at placard price than it is today. People are unlikely to pay any price that would support a market.
Sure, originally my post started out "If instanced housing or wards 25-80 are coming in 2021, then this is all moot" but I decided to move it to a footnote (my edit on the OP). I moved it mostly because it disrupted the post flow, but also because my suggestion is being made with a mind toward housing as it is now, rather than housing as it should be. My suggestion is coming from a place of "If only 1 in 5 players gets a house, how do you we pick which one?"
*source: https://i.imgur.com/PJfSdux.png courtesy Y'shtola Cat