I agree. One reason employer medical coverage has worked so well for decades is that nearly everyone was enrolled; I suppose there were exceptions for people who were on a spouse's or parent's plan, but since there was little incentive to opt out when the employer provided it at little or no cost to the employee, the insurer got the healthy employees, too. (And, of course, even being healthy enough to work FT meant lower costs on average.) You couldn't game the system by waiting to enroll till you got sick because typically you could enroll only when you started, as of January 1, or if certain qualifying events happened (e.g., married, spouse lost job, etc.)
Medicare has similar requirements. If you hit Medicare age and don't immediately start Part B and prescription coverage and try to enroll a few years later when you get sick and/or get an expensive prescriptions, you'll get hit with a permanent surcharge on your premiums. The only way around it is if you had "equivalent coverage"- in DH's case he signed up when I retired and I was 61, he was 76. He'd been on my employers' plans so there was no surcharge.
