Jump putting is harder to enforce than the 10m circle for two reaons.
1. The determination can be made prior to the throw. The thrower can ask if he's in or out. This gives the group an opportunity to come to a consensus and make a definitive ruling prior to any throw being made. Sure, the difference between 10m and 9.9m may be hard to eyeball, but at least you can get group consensus easily.
2. Even if a consensus isn't reached prior to the throw, the lie is still on the ground and can be evaluated after the fact.
Jump putting is all about timing of both the plant foot leaving the ground, and the first contact in front of the lie. To enforce the jump putt rule, the rest of the card needs to watch very carefully for timing of release of the disc vs foot contact with the ground. There is no opportunity to review it rationally after the fact. If someone makes a call, it's entirely based on recollection which means it can lead to some heated arguments that can not be resolved with reason.
The closer you get to the basket, the more advantage there is to be had by leaving the ground, or following through a little too early. For a fairway shot, the advantage is negligible, at 10' it's huge.
It's impractical to force every shot to have no follow through, so you have to draw a line somewhere. Currently that line is at 10 meters. It's far enough out that watching the intricate timing details becomes less necessary, but close enough that it can still be eyeballed fairly reasonably.