I've never been primarily a developer but I have worked in areas where one of my primary outputs is writing. When I've hired for a similar role, if someone doesn't (for whatever reason) have writing sample(s), they're not going to get hired unless they produce one. It doesn't have to be an assignment; choose a relevant topic. But I'm not going to trust you that you've done tons of great writing if I can't see it.
And that may take a day or two.
>confidentially
But yes. One can imagine someone writing non-public reports and analyses for internal or client use only and just doesn't really do that kind of thing in their spare time. Myself, I have tons of public material but I've also written many things I couldn't share.
I did one, once. I liked it initially; if my skill set isn't quite up to par, I can spend 10 hours on something they expect to only take me 5, and so I have a better opportunity to impress if I'm really interested.
On the other hand, I tend to get along very well with people, so I "interview well", and I like the on-site thing because it's time-boxed. I either get the job, or I fail, but at least it's over, and doesn't drag on indefinitely.
Those things are a hard "no" for me.
10 hours of interviews... I might not like it, but at least it's symmetric. People at the company are putting their time in to the process as much as I am.
But with a job, kids, hobbies, volunteer work and so on, I just pass on companies that have day+ long 'coding challenges'.