> one with all the problems passwords always had
No, because the PIN is tied to the device and becomes invalid much more quickly. A Windows password is potentially used in far more places and potentially across many devices.
> I guess the idea is that it is easier to use
For many, it really is. On some of my devices which lack biometrics my pin is just a few numeric digits easily input with a small numberpad. The PIN is backed by the TPM which wipes it after too many failures. This is far faster and easier to type in than my full Microsoft account password which uses most of the normal complexity concepts such as length, mixed-case, letters+numbers+symbols, etc. Far easier to just type 4-6 digits (or however long you want it to be) instead of dozens of mixed-case alphanumerics and symbols.
For instance, I recently got a gaming handheld which runs Windows. I want to use my Microsoft account, but as mentioned its a long and complex password. It seems this device doesn't have any biometrics, so its either type in my very long password every time the screen locks on a software touch keyboard or just type in a short PIN backed by the TPM. Which seems like the better process?
> it feels like
You may feel that way, but a Windows Hello PIN is not a password. They're different things in many ways. I could continue throwing more documentation at you, but somehow I feel like continued facts aren't going to change your feelings about this.