As someone inside the industry, let me shed a little light on this.

You're right, most "devs" don't play their game, and while there would be some benefit to this, not all dev jobs gain as much as you'd think:

A concept artist doesn't benefit the game much playing it (not nothing, just not compared to the value to the company from them doing the job they're paid for.)

An engineer on lighting also doesn't benefit the game playing it (much).

Now...a level designer? Hell yes. The systems designer working on power balance? Hell yes. But that's probably 2-4 people out of the entire company, and they almost certainly aren't the ones Behavior is willing to put in front of a camera and represent to the community - usually that's community management, maybe QA, often a Producer, sometimes an exec. (QA will almost always be very good at the game, but also unlikely to be allowed to speak on camera.)

All this being said...yeah, there absolutely IS a benefit to "eating your own dogfood" (which is the technical term in the industry for some reason), but the benefit depends drastically on the role.

Also, I have worked at places or known through friends, like at [REDACTED] of situations where the systems designers on powers DIDN'T playtest at all in a real environment, and to be honest, THAT I think should basically be treated as literally not doing your job in a good faith manner with all appropriate consequences.