No unrestricted traveler for sure unless they are traveling with others on a separate ticket.

More applicable for some, some organizations which are allowing PremPlus but not Business . So, they will purchase PremPlus and then try to upgrade (an upfare is the smart route although the refund could be a problem).

This is similar to when economy was more expensive than domestic first. UA has most fixed that problem with domestic first a fare differential over economy. But a few years back it was reoccurring issue.