I agree with this. After spending 20 years in dev and several of them as a team lead, the vast majority of the project managers I've worked added very little value. Most of my interaction with them fell into three categories:

- Asking them for project priorities and waiting while they asked management for the answer.

- Giving them project updates and then listening to them repeat those updates verbatim during the next day's meeting with management, that I was also in.

- Asking for their opinion on how something should work, just because I didn't want 100% of the blame when management didn't like a decision.

And honestly, saying they had no value-add is being generous. The majority of the examples listed above were time sinks.

Of course there's the occasional good PM, but they were very rare.

>90%, maybe 93%, of project managers, could probably disappear tomorrow to either no effect or a net gain in efficiency.

As a prior PM, I agree. We're there to help management, not the engineer. The engineer does not care, and it does not raise efficiency. I always felt bad about this, and went back to engineering.