there is much truth in your words.
In Chile we have had a few cases of NT players in D.III but a few were on teams that relegate from D.II. The mayority home made players(draftees) and some early buy.
Most teams who has NTM trained in D.III and then promote to DII with their star.
Miguel Turpin
(4754222) was drafted by me in D IV in Season 4. With him leading my team i made it to D.1 in S17. Now with 37 yo he is still the Infested Warriors's Franchise player and will lead again the comeback to D.I.
I'm proud to say (maybe i'm wrong) Miguel Turpin is the BEST 37 yo player in the BB World. 19 years playing in the same team, born and raised. 2 times MVP (D.II), 2 times American Champion and World Champion with the NT.
Trainers with carrer extention are TOTALLY worth it.
PD: I think i'll gonna cry, almost 5 real years and this story... is going to end sooner than later. :'(