I will occasionally file bug reports or even submit fixes to open source projects as part of doing my job. As an engineer, one of my responsibilities is to maintain the commons - without it I would be much less productive. On the other hand I have a lot of autonomy in my work, a chill boss and a team that doesn't need to crunch. If someone I report to got grumpy I would stop, and I definitely don't do this on my own time.

I think that applies to a lot of creative industries. Certainly when I was looking to be a designer some 20 years ago you were expected to maintain a portfolio.

I don’t even mean in that sense though, I just don’t understand having a skill like that and not using it for fun.

For what it’s worth, the best salespeople I know have almost no purely home life and are taking calls and making deals all hours of the day.

Assuming you treat your creative job also as a hobby, while nt doing so is also perfectly ok, doesn't mean your work has to be public, right?

Still, hobby projects are not a portfolio.

They are when you haven't other things you can show show.