I agree that being forced into 6% commission regardless of the effort it took to buy/sell your house is a problem, I don't think that extra few percent is what's pricing people out of buying a home.
The effective cost implications are more likely 10-12% at each sale. A seller will try to increase the price of the house to cover these commissions.
Your comment is focused on buying a home, but there can be dramatic consequences for home owners, the stakeholders forced into paying both agents.
When a seller has little equity and a poor housing market, exiting a primary mortgage can be financially impossible. A recent survey found a large fraction of the US can't handle a surprise $400 expense. So the follow-on effects of these commissions are not trivial for a large swath of the country.
I also agree that depending on location (looking at you SF metro) there are much bigger factors, e.g. constrained supply, inflating home prices.
