If you did it before then, barring physical limitations which have occurred since then, you would struggle for a short while and then you would be fine. I also did coursework purely on paper, got out of practice, and then once my kids were in school got back into the habit of handwriting. I can even write cursive again. Cursive makes it much easier on the hand and wrist. There's a reason it was invented. :)

I think you're missing the point. This is a physical limitation. People don't write as much as they used to. I used to be able to write for hours, taking notes, writing papers, etc... Now, I try to take notes during a meeting and my hand cramps. And as a bonus, my handwriting never was great, but now it's illegible for me.

Yes, we all "could" re-learn this skill, but how many people will? If you asked me to type a paper on a locked-down computer, I could easily. If you asked me to write a 2000 word paper by hand in an hour, I doubt it would happen.

If we expect students to take in-person tests on paper, then you should also do the rest of the classwork on paper. I am completely in the camp that we learn more when we write something. The physical act is part of the learning process. But you can't expect students to write an in-depth exam without having the practice of doing it often.

Are you using a fountain pen, writing cursive and do you take care to hold it properly? Those three things fixed all my cramps

For righties.

I'm right-handed, but I had to learn left-handed cursive at school when I spent 5 months with a cast on my right hand.

There will likely be a period where those who went through high school with computers struggle with hand writing stuff, but the next generation will have done it all their lives.

Say what? Writing by hand is not only useful to write. It helps practice fine motor control. Something you need in many places in life, and most people have no practice of other than by writing.