This is equivalent to asking why competing firms don’t simply agree to collude to stop innovating and fix prices, except in this case the colluding parties lose

This is equivalent to asking why competing firms don’t simply agree to collude to stop innovating and fix prices, except in this case the colluding parties lose by paying a toll as opposed to reaping monopsony profits. Given a meaningful incentive to do something within its means, a company will either do that thing or lose business to companies that do.