I always thought this was meant to happen one day and honestly, I'm happy about it. Things were getting out of control.
In the beginning, there were few teams making moves with young players with potential 9-11, but nowadays the bubble was about to explode. There were so many people trying to make money out of these players that the transfer list was a complete joke. For example, Poland 1st division has become a jumble sale
The same thing happened some time ago: I and a couple of other managers used to trade grandpas with SOS 10, and many other people started doing the same. BBs decided to stop it and start fining.
One very important point that I would like to mention that did not appear among the guidelines: training. A couple of pops can dramatically change the price of a player that has been recently purchased. For example, the player that Gatienextra mentioned and I sold a couple of days ago had improved in 5 important skills (plus some others in which he was about to pop), and therefore improved his price (which was btw an absolute bargain when I bought him). These types of sales should be fine. However, I'm happy with the fact that the sales are punished if they are pure speculation with players who did not even train. For example, I was recently fined for selling a couple of players with pot 11 like this one
(50871775) and I was absolutely OK with it.
I would like the guidelines to be as precise as possible and contemplate as many scenarios as possible to make it clear what will be punished and what will be not.