If those groups can convince a decent percent of people to spend the max that they can get away with, it doesn’t matter what you do personally. Prices will inflate because most others are still spending big.
The differences among households' incomes are already higher than the reasonable ratio between the max approvable to borrow and the sensible amount to borrow. (A household making $300K can already sensibly borrow more than one making $100K can be approved for and one making $100K can sensibly borrow more than someone making $30K can be approved for.)
Households are still competing with others to buy individual properties, of course. That competition doesn't mean that you should YOLO it with the largest purchase most people will ever make just because others are willing to do so.
Of course those groups urge you to spend the maximum: they're all being compensated if you do exactly that.
At the end of the day, it's still you who is signing the contracts, responsible for how you spend your money, and has to live with the outcome of your decisions.