At the last job I had which offered insurance, the only way anything was taken out was if I chose to enroll in the insurance program. Prior to enrollment I paid nothing into the pot. Perhaps it was an isolated case? I worked for a university, though I’m not sure that’s relevant.
I have found that the plans I could have gotten via the above link were much more affordable and equally beneficial as what I had via the university.
I don't doubt you. But generally the employer is paying some portion of the insurance premium (out of your total compensation package) but will not give the money if you choose to buy elsewhere. So you lose that portion of your compensation. In your case, either the amount the University paid was small, or the discount you found was exceptionally large.