Botting on the marketboard. Impossible to sell anything.

[Seraphor]

I don't write their software, so maybe it is more difficult than I imagine it. As a software developer by trade that commonly has to rework other developers' code, it doesn't sound too daunting. They already take a fee when it sells. Set that fee to 0%. Add a fee when you list of 1% or whatever. That triggers anytime a player brings up the "Adjust Price" window either by clicking "adjust price" on an already listed item or "Put Up For Sale" out of your own (or retainer's) inventory.

However, maybe they are dealing with spaghetti code worse than I deal with daily and isn't a simple fix. Or maybe they just don't care to address it.

This would just lead to more extreme undercutting.
If you have to commit to your listed price, you're not going to risk undercutting the current lowest listing by 1 gil when there's a very real chance you'll be undercut in a few minutes anyway.
May as well get ahead of the race to the bottom and place your item for sale 100k lower to start with.

Not everyone is trying to play the system, most people just want to get rid of their junk, and you only have 40 slots as standard, so you can't have these things lying around for weeks waiting to sell. Price low to get rid of them ASAP.