In a lot of organizations a Lead Dev is still a coder, but keeping an eye on the long game.
Personally, I think that the sort of code you're talking about here is a big part of the mix of things that a Lead should be working on, or at least championing. You don't actually want these people to have too much code with their name on it for the same reason you don't want Managers to do it: It gets treated as a sacred cow whether you want it to or not.
For myself, I'd estimate it's about a 40-40-20 split between DevEx code, the most safety-critical functions in libraries, and example code respectively. But, I'd aspire to flip the last two numbers (on a high functioning team I should be able to trust other people to do bits I barely trust myself to get right).
And unless you enjoy bottlenecks (some people do because it makes them feel special), you should be trying to get most of the code written by people of average skill (the peak of your employee bell curve). So if I'm writing even half as much code as they are, things aren't going well at all. You want a light touch.