I was paying <~$300/mo on that plan. I now pay over $700 on a directly-acquired plan. So that's problem one.
The bigger problem, IMHO, is that quitting means changing your insurance, which isn't just a financial change. It can also end up requiring you to change medical providers, which is no small deal!
This adds massive friction and stress to the act of quitting/changing jobs, a major source of leverage on the employer's side.
And that's to say nothing of the fact that it's effectively an overly burdensome tax on new entrepreneurs. It's a reinforcement of the concept, "you have to have money to make money".
JMHO on the topic; for reference, I'm a new entrepreneur very early in the process. I'm just lucky enough to be able to risk the attempt.