RE: Three Tiers (long) No, just well reasoned.
The classes I put together were more or less off the top of my head and secondary to the discussion. My thinking was allowing sufficient overlap for progression.
The main point (for me) was one overall North American sanctioning body, common rule book, a common seeding list and a well defined (three) tier system providing a development ladder for drivers, co-drivers, teams, service people, organizers, workers... Put the manufacturers right at the top and don't step in until you've got what it take$. Make the top tier FIA classes because the next step would be WRC. (I know - that sounds crazy)
I realized about 2 seconds after posting, that my proposal was far too reasonable - that someone would narrow in on... say the class structure, for instance.

I am naive.
Hokay - back to class
I missed Group 5 because we don't have it up here and I forgot that it existed - don't want to get into an argument over whether it should exist or not.
I personally believe that beginners should not run Open or Group N class cars - but hey
I never really liked the multiple production sub-classes either. Maybe a return to P, PSport & PGT - I don't know.
I run a production car - an NX2000. 2500 lbs, big brakes (same as the Pulsar GTiR AWD turbo), VLSD, 4.18 to 1 final drive, a great motor (SR20DE - 140 hp, 130 ft.lb), available gravel suspension (DMS, Bilstein, Hot Bits, Morriss), easy/reliable/relatively inexpensive upgrade to Group 2 (SR20VE, cheap & available dog engagement gear set at any ratios T/W R&P, existing Group A suspension & driveline pieces from NME's F2 Pulsar GTi - BRC championship: Mark Higgins). You get the picture. It'll be a while before I'm driving faster than this car, even in production trim - I think you could say the same about a lot of drivers.
To absolutely prove to you that Production is a useful training ground for beginners - exhibit 1 = ACP. From pokey Lada to ex-Tuthill Open EVO - and not tripping over himself (understatement there)
I've had the pleasure of taking a 'clubman A' Escort Cosworth RS for a spin. Fast car, but a serious learning curve. Even if I had the money, I would be inclined to stick with the P car for now.
These are just my opinions, I would be very flexible about changing them if the main point (North American sanctioning) were achievable.
Robin