Here's the thing, cohabbing is only a huge deal because 99.9% who try to do it, do it horribly wrong.
Huge wardrobe sized tanks where the snakes have many warm and cool spots to choose from is totally fine. It sort of mimics overlapping territories in the wild. VERY VERY few people actually do it that way. (I'm talking huge, zoo level type enclosures)
What you see 99.9% of the time is people being too cheap and wanting more snakes than they have space for. Jamming two full grown corn snakes into a 20 gallon tank is cruelty. They are forced to be right in each others face at all times. Even two adults in a 40 gallon is not acceptable. Still not nearly enough room to get away from each other.
Cohabbing like that can lead to stress, cannibalism, premature breeding, unwanted breeding, illness and death. That is not speculation, it's a fact. There are many threads on this site with evidence of cohabbing misfortunes.
Snakes live alone in the wild, numerous scientific researches studies prove it. They may have some areas of territory that overlap, and once in a while a few may share a den, but then they move on. Having a few kilometers of land to run around on and once in a while bump into a mate or other snake, is not the same as being stuffed in a tank with other snakes.
Snakes do not for bonds, cuddle, or mourn for cagemates. That is people putting anthropomorphic feelings on animals. Snakes are very basic creatures.
Cohabbing done strictly for the keeper's benefit. The is no health or well being benefit to the snake.
Keeping a pair together for a stretch of time during breeding is okay depending how it's done. You have to keep a regular check on them and make sure you are not seeing aggression. There have been instances where males have killed females, and females killing males. Don't keep them together longer than necessary. In the wild they mate and move on, they want their own space.
The bottom line is we as keepers should strive to provide the best care possible for our pets. Snakes get exactly zero benefit from cohabbing, so why would any caring keeper do it? It makes no sense.