That's a hack that is often described on HN, but the point of COBRA is, as the name suggests, continuity (originally, in part because pre-ACA an issurance gap itself had adverse consequences to future insurability, and acquiring private-market insurance isn’t typically instant, but also because people often have ongoing medical needs where a discontinuity in coverage could disrupt service, )

Yes—something people today might not know is that before the ACA, you could be denied insurance coverage for "pre-existing conditions," which in practice meant anything medically recorded before you were insured. Changing insurers (because you changed jobs) didn't reset this period, but having a gap over a certain length did—I believe it was 60 days. So it was very important to make sure you maintained coverage, or else your ongoing cancer/arteriosclerosis/diabetes/etc. treatment was suddenly 100% out of pocket.

Also, COBRA and medical insurance in general used to be a much smaller fraction of middle-class take home pay, so it was a lot more realistic to elect to pay it out of savings even if you weren't concerned about all the above.