Um. It most certainly is for at least some vendor-supplied Android builds, in my experience.
It may not be necessary for all Android activations (particularly CyanogenMod builds), but there are phones for which this is at the very least a practical, if not essential, requirement.
On my Nexus 4 and 7 you can answer that you don't have a google account and it will allow you to set it up without one, this has been the case on every Android distribution I've seen. I don't think that Google or AOSP builds have ever required a google account and it's not really fair to blame them if a particular vendor does.
Tying indeed. DOJ?