> average consumer is with their health insurance provider for about 3 years

Are they? That sounds right for how long they're with an employer, but if I move companies I'm probably going with the same insurance carrier under the new company's plan. The total list of carriers [0] is pretty dang small (and not every licensed company is doing new policies).

Even if what you say is true it seems like reciprocity would make up for it - Company A pays and Company B benefits like you say, but for every situation like that there's a situation where Company B pays and Company A benefits.

[0] https://www.insurance.ca.gov/01-consumers/110-health/20-look...