Even if your team is self-organizing, eventually you'll need a "Tech Lead". This person really isn't a boss. They're more of a facilitator that handles all the cruddy work so that developer productivity is maximized and the dev team is free of distraction. They also manage the "politics" of the dev team to the outside -- like making sure strong devs get recognized for their performance, and weaker ones either get mentored (or if that doesn't work out, fired).

I've worked under 30% leaders before and didn't care for the experience as a subordinate. I always felt like POs and PMs broadsided the team, good people weren't recognized or rewarded, shitty people got to hang on, etc. The experience wasn't awful, but it wasn't that great. It would have been much happier had our boss spent two fewer hours each day coding and 2 more hours managing each day.

Also some 30% tech leads tend spend that 30% needlessly micromanaging developers on their team by doing stupid shit like constantly having them move classes or modules around the codebase for no rhyme or reason towards better "organization" rather than just telling the team "I think the way x y z exist is messy. When you have downtime, or are sick of working on whatever and need a break, can you folks think of a better way to re-org and refactor them?"