Maybe you are missing all the points.
But I want to make sure that anyone who lists the player, has a plan to actually sell him
Why? It could be useful for other reasons. And if I want to put a palyer on TL not wanting to sell him, I can overprice him, why not? As long as I report if someone bid accidentally (come on how often that happens) there is nothing wrong with it.
And on the other hand why should be managaers pushed to sell players ASAP? If I don't want to sell a player for less than X because he is worth at least that for me it si completely fine. In this case I am eithe desillusional or sooner or later market evolves the way I can sell him for that price or someone needs such a players badly and I would be at the right place at the right time.
With the suggestion, market could become much more dead , silent and unpleasant place because it would be a buyers' market even more and that would lead to less amount of player on the market (with the exception of high salary players their clubs cannot afford to have anymore).
When something is working well it needs to be changed obviously, I don't get this.
Disclaimer - I'm not buying or selling much (as you can check).