Well, the issue with that is if your a fan of the series, lets say, gundam for example, its a good example, there are design patters that are EXTREMLY obvious within the diffrent factions. If you know your series you can look at any mech, even if you never saw theone its from, and tell what faction it is from, and generally, what era as well. There are distinct characistics about everything in gundam that makes it hard to scratch build because everything does not go, technichly, for this. While you can do that, alot of the time its obvious it doesnt fit together. For example, there is a LARGE and obvious draw from WWII with the designs, there is ALOT about Zeon which reflects the nazis, the uniforms have an influence, as well as the designs of some of the things, the names, and the weapons (many of them being taken straight from wwii, if you watch the video, the Zaku bazooka is quite the same as a us bazooka, the Ric Dom's bazooka is clearly a panzerschrek. If you look at the figures, they bear a resemblence to British commandos, with the berets (there north western european divisions)
As you said Karl, the design does look like an almagamation of a few diffrent tanks, if you watch the epi linked, they reference that. Its an Earth Federation Tank, the our timeline, and the timeline in the series divulges sometime after the moon landing, and that only being with the scientific discoveries involving space travel and such, it lends that at one point, after the governments of earth formed one government (EF, Earth Federation) that designs were mixed to create, as they say in the series, a variation that completly outclasses it's predecessor, and its the 5th form of it, quite like we have multiple forms of our vehichles now. They give rhyme and reason for the majority of the designs they have for this series, its not necesserially done whilly nilly, as some series do.
By the way, I <3 you for linking me to Ms Igloo 2, I have been searching forever to find that online, though, I miss the opening music from the first