I think the reason most aftermarket cam require the VVT to be locked is because you can easily cause some PtV problems if you aren't dead nuts on the tune.
I agree. Easier to lock it out rather than have some knucklehead blame the issue on the cam manufacturer even if it could be kept.
I see that Summit is adding cams from Brian Tooley Racing for the VVT motors, and the lower end range is using a 4 degree limiter instead of locking it out.