I've rarely had managers that did not have technical chops.

Did they know the ins and outs of fashion in the latest JavaScript frameworks? Not always. Were they sometimes rusty remembering the method signature of standard library functions? Yeah.

But they typically had deep knowledge and experience with architecting systems, maintaining those systems, making important strategic tradeoffs, planning and estimation, reviewing code, and interfacing with the business.

Having a manager with these skills is invaluable for a productive team.

Most technical managers (like myself) come from a development background. I personally have a very strong fear of not having the technical chops to demand specific behaviours & actions; of being illegitimate. My group's staff developer was very close to taking the job that I now have, but decided he wanted to be a technical leader. I do all the stuff that gives him the time to do that.

Sounds like your team is lucky to have you. I know not all teams are in a good spot in this regard. As you mentioned, not all engineers want to end up in your role. Good managers create the conditions necessary for architect/staff engineer roles, and engineer career growth in general, in addition to achieving business goals.

Line managers should definitely have technical chops.