Agree. However companies that don't pay their bills AND fail to inform their employees of that fact ought be met with scorn precisely because employees themselves could find alternative coverage if necessary and informed. I think it is unreasonable to expect employees to check every day or heck, even every week that their coverage is still active. I would think it is the employer's responsibility to actually SAY "hey you aren't covered anymore".
EDIT: In other words in principle I agree with your notion that working for a start up is a high risk, high reward proposition, but there are still basic matters of human decency in play, and those include actually telling somebody "you don't have health coverage anymore" or "we weren't able to sell your house" so that people can plan accordingly. It would still suck to be told those things, but at least you would have a chance to do something about it.