Could re-installing the "gatekeeper" referral save on health care costs in the U.S.?

[winter is coming]

6. You need a good PCP for this to work.

I've had the same one for almost a decade, and she's a gem. She's the first doctor who hears whatever the problem is, then refers me out to the appropriate specialist. If we reach a point where the problem has migrated from acute to chronic (e.g., I'm in a steady-state mode on some sort of treatment), I go back to her for the routine monitoring -- there's no need for the extra expense or wait times involved with seeing a specialist.

OTOH, I had undiagnosed hypothyroidism many years ago and the "gatekeeper" plan I was on delayed my diagnosis by two years. More than one PCP decided my problem was depression and wouldn't consider testing anything other than my TSH, which was "fine". It wasn't until I switched employers and got on a PPO plan that I was finally able to see an endocrinologist, who told me I had Hashimoto's thyroiditis, and based on my symptoms and history, had had it for years.

When I first starting looking for help, I didn't know what was wrong with me. By the time I finally saw the endocrinologist, I'd been increasingly convinced for a year that I had a thyroid problem but couldn't convince any PCP of that. That experience makes me strongly opposed to "gatekeeper" plans, although I think it's a good idea for people to self-impose that model as a first option.