1UPT is bad. That is a given, not really up for argument. It's been deconstructed so many times by other people.
That is not a valid argument, sorry.
Any variation on 1UPT that could work involves a finite stack limit of sorts. However, creating this limit would be based on
preference rather than any strength of games design.
Any comprehensive UPT modification would have to involve AI work to account for the changes, something to date I don't think anyone has attempted (definitely not for BE, not sure about CiV).
This is why the argument generally boils down to "1UPT" vs. "MUPT". Imposing a finite limit on MUPT has no decent design grounding because what people find an acceptable limit in the strategy vs. tactics payoff will vary. For some people 5UPT would be too much. For others 3UPT would be too few. And so on, and so forth.
A better thread would be "what problems are posed by 1UPT and how to resolve them". Modders have already made great efforts in this area - the map generation code is a bit rough and benefits a great deal from refinement; the Pandora mod for BE really polishes up terrain generation and (optionally) resource placement. These two things in of themselves not only improve strategic options for army movement, but they also improve build diversity by improving available (Affinity) resources.
tl;dr: there are issues with 1UPT, there are issues with MUPT; it largely comes down to personal preference despite the design strengths and weaknesses of each.
I consider 1UPT superior, but that's because I prefer the
tactical army map compared with the
strategic faction map. It's cleaner and thus leads to better design when compared to a muddle of tactics and strategy on the army map vs. mostly strategy at the faction level.
When you have a clearer design goal for a particular segment of gameplay, you end up having better design.