Re-installing was only necessary before Windows 10. You can still do so in 10, but it's not necessary. I've taken hard drives with 10 installed and transferred them to completely different desktops(even laptops). Only real issue is you may have to re-activate Windows. It's always good to do clean installs of the latest drivers from the manufacturer's website regardless.
Oh and I have even gone as far as to pull a drive(with 10 on it) from a Lenovo laptop and popped it into a Macbook Pro. It still booted right up to 10 and worked fine. On my most recent build/upgrade, I switched a desktop from an Intel based board to a AMD Ryzen based. I didn't re-install Windows on that either and everything is working fine.