I think dedicated project managers are a good idea to keep people focused, but I also think if you've been buildings things for 20 years you should have absorbed enough of the process to be at least basically capable at it. That's not really true of people management (an entirely different skillset) or technical writing (though it's a bit closer) or even product management (but if you code mostly customer-facing features, probably you should have picked up a lot of this too).

If you've just been a "turn the crank" developer implementing someone else's sprint-scoped tickets for 20 years, you probably topped out after around five years. (Or you're doing all the interesting stuff outside work, in which case... you definitely have project management skills.)