The vast majority of drivers are stupid. Even more of them are cheap. I’m honestly happy car tire places have this policy because it makes it harder for these cheap idiots from totally fucking up the handling of their vehicles.
If you’re too cheap to buy 2 more snows and determined to drive that way just rotate the tires when you get home. I don’t care if you’re a pro rally driver, on the street you’re a lot safer with 4 snows than 2, especially if you’re putting them only on the front.