This is certainly true among some managers, and is also how you wind up with useless project managers and "scrum masters" who can't actually do anything except send an email or slack.

Is this based on something or just your perspective?

Observations really.

I've seen this pattern many times on smaller and larger scales. Betting on a technical manager is almost always the correct bet to place.

Being an internet commenter doesn’t require any particular expertise in the thing…

I think GP’s claimed belief “among managers” is true for a very small sliver of the management ranks (and I think a smaller sliver than in the internet commenters’ case).

It certainly seems true of a breed of MBA. When interviewing candidates for PM it's interesting to see the breakdown in people who care about how the product works and those who consider it a widget to be put in a box. "Bring the customer demands to the eng team (without providing a useful translation)".