Depends on the country.
Lets consider the US.
I would say that all starters should have a minimum of 40k salary.
I am glad you're sharing all of your vast experience as a division 1 manager, but I don't think reality lines up with your claims. So let's consider the US:
I randomly selected a team: Bobo's playhouse are a playoff team (4th place) in the NBBA and this is what the salaries of their wing players currently on their roster:
$62k
$29k
$16k
$14k
$11k
$8k
Plus some sub-$5k players that I assume just balance out minutes.
Now one has to assume that at least two of their starters are below your imaginary threshold unless they've got centres playing point guard.
The starting small forward for Heathens (6th best team in the world, top ranked in the US) is below $40k as well.
I think that in general there is something to be said about top teams not generally training a ton of young players and instead buying already partially trained players in their 20s to continue their training without giving up too much, but I also think you're way overstating the case.