And frankly, when you hire a manager or executive, there's not generally a single artifact that you could use to examine their value-add. You can see perhaps the trajectory of a company or a division or the size of their team over time, but you can't see the pile of ongoing decisions and conversations that produce actual value.
I think the flip side regarding code is, the stuff I do for fun outside of my employer's IP is not at all representative of what I do at work, or how. I pick topics that interest me, work in languages that my company doesn't use, etc, and because my purpose is learning and exploration, often it doesn't end up as a finished, working, valuable piece of tech. I deliberately don't do anything too close to my actual work both b/c that just feels like working longer and because I'm concerned it would make ownership of the code a bit fuzzy, and perhaps it would be inappropriate to consider open sourcing. Because my side projects are eclectic and didactic, I rarely put it in a public repo -- but it has served its purpose of teaching me something. If I shared all of my code side projects, they would show an unfocused person dabbling in a range of areas and not shipping anything useful, because that's what's fun ... whereas at work, I am focused in a few quite narrow areas, and working on customer-facing features, because the point is to build what the company needs rather than what I enjoy building.