Sounds like a day trader tool,
if this was to happen it would have to be limited to only 1 autobid on 1 player at all times.
Yes, this is the issue which can be solved easily and also is the question when autobid should happen. Right away after opponent make a bid? I suppose that user will get to recognize this behaviour by the time.
So the question is why someone doesnt bid a maximum value right away instead and want a tool to save him the money. It is because you never know who and when will overbid you. Its a pretty live market. The reason why most of the managers overbid is because they hope that you give up. So when there will be autobit mechanism, most likely happen that user will give up sooner.
On the other side is true that so many players are sold cheaply, because there is no time. So I think that there could be some kind of autobid mechanism, but only that which is there for a checking that the player will be bought for a maximum price you already putted on.
I mean sometimes happens that you put 1M for a player, go to sleep and when you wake up, you figure out that he was sold for like 1,15M to someone else. So I think that when I bid for a player which I believe is really sufficient to "risk" the price, I could tell to the coach to have a nightshift and he could randomly overbid to 15-100 percent from the maximum value I putted on.
The difference is that you have to put in some money already to have an autobid. And the result will be somehow random, because instead of minimal overbid, he could buy (if you are unlucky) that player for like 1,8M.