Chances are that if your employer isn't willing or able to pay for benefits they're also not willing or able to pay for a maximal salary though. You're probably just missing out on benefits rather than being paid the value of them. The companies shareholders and owners make more profit though, so if you're getting compensation in stock you are benefitting indirectly.
a. what is the total compensation paid to the employee?
b. how much value will the employee produce?
If `b` is less than (`a` + opportunity cost), then "no hire". What percentage of `a` is salary is simply irrelevant to the business decision.
Your supposition is only correct if the business manager is winging it and has little idea what is going on financially in the business. The field of "cost accounting" is devoted to figuring these things out. Getting a good handle on it is key to running the business efficiently.
