If the goal is realistic simulation, then constraints are necessary on pretty much everything in order to properly model how real life works. In real life nearly everything has a cost: time, money, effort, resources, PR, goodwill, reputation. These combine to impose de facto limits on things like signing and releasing players.
Right now, those limits don't exist in OOTP (the closest they come is the roster limits, which seem to be off by default). I wouldn't say this is a
problem per se -- as I mentioned, a player can simply use self-restraint -- it's just a bit of a weakness in this particular area of the sim, because "rules as written" you can go absolutely nuts signing free agents and there is no cost whatsoever.
"Seems like a time-waster to me, since I can't imagine you're getting a much better quality of player for all that effort."
Ever play as the 2018 Marlins? Hoo boy.
The entire farm system needed "renovation."