First Programs Rating 10 is the limit, so your 20 doesn't exist.
Tell that to a starting Technomancer.
By the time a hacker could conceivably have a single R20 program, according to the suggested karma/nuyen growth standards, a TM could thread all his CFs to 16, with options, and get Sprite-related DP bonuses of 8-12 from Assist Operation and Probability Distribution.
I only told what is written in the "WAR!".
And pointing on Technomancers isn't a solution. Btw. your example is flawed. If a Technomancer would like to have a CF at Rating 16 she has to have at least 8 in her Resonance Attribute, and has to resist a fading of 8 DV (Physical), and get -2 to all other tests. Sure you can push CF with sprites, but first of all you need a registered sprites, and they are usually limited by the Charisma Attribute of the TM, and it takes time and fading, too. But if she does it, Assist Operation is only temporary, so it is a juice for hardcore times (a couple of Combat Turns) and not 24/7 available. And usually as GM it is easy to juice the TM out. And since fading damage and Matrix damage are real Damage only a tiny little part of specially designed (PG) Technomancers could live long enough to get more than a couple of this CF running.
But you are right, it is possible! But I doubt that any TM could raise all of his CF to Rating 16 at ones.
And if a TM could pull up the stand, it isn't a stable one, any GM could throw him off at ease. One time consuming Matrix action, like an encryption, taking a couple of minutes and *puff* there goes the task and another and another...
I don't say that Technomancers are not good at this or powerful. But most of their powers and tricks are only temporary, and need time and often pain to recharge.
And I do understand that hacker players want things like that, but is a new limited Rating 10 for programs really the answer of there prayers? I doubt that. I think, the impact is at the moment really unforeseeable, but in a couple of month we will see, how it works or who uses it for their play.