But in the enterprise, so few people need to talk to anyone but other tech people, the interfaces to the outside world are few and far between.
I agree here, but there is a minimum viable product of soft skills where even other tech people don't want to put up with your shit, or your ability to communicate with other tech people is crap and so you don't get good feedback or collaboration. The 10x engineer who belongs in a closet is something that fewer and fewer companies will put up with. Hell Linus recently admitted he needs to stop being an asshole. Netflix has an official policy to not keep them.
Lacking soft skills doesn't make you an asshole, though. That's not the alternative. Soft skills is a lot of things. Being nice isn't one of them. Being nice is just being a good person. Seeming to be nice when you are actually an asshole, now that is a soft skill.
I worked with a guy like that. Came across great, but openly admitted he was a horrible person that would screw you if he could. Great soft skills, mediocre hard skills, not a nice person.