That sounds a bit like "the reason for this traffic jam is clearly that there are no enough lanes".

Evidently, there are enough buyers/renters around who can afford the higher prices and are able to price out the $30k/year group. So what would prevent rent or prices from rising to the same unaffordable levels in the new development, if there is still demand from this higher-paying group?

I feel if the market rate becomes unaffordable for middle-class fulltime employees, then you have an inequality problem, not a supply problem.