So much of what you say is wrong, as well as you talking about things in Mario kart that i've never witnessed nor heard about despite my many many hours with both versions. I'm suggesting beyon3d to you so you may challenge your assertions with more people than just me, because it's tiring when you're this wrong and you're not going to listen to one gaf poster. Hell even DF have useless tools according to you.
If you were providing information - and it was correct - I'd happily accept your info as fact, but you keep telling me things without substantiation - seemingly because you don't want to accept that a cornerstone of a Nintendo home console - splitscreen multiplayer - is better served on the actual home console they released 4 years prior to their hybrid console's launch.
I asked you to elaborate on your asserted 59fps drops in MK8 on WiiU because I actually checked their video back in the day with a video editing package with the histogram viewer on, and stepped through their claimed frame drop section, and had unique histogram graphs for every frame - concluding all frames were unique. And as you were so adamant that you can tell it is 59fps, I was happy to let you elaborate.
Like your statement on Wii U bandwidth, no it isn't a "by product of Wii U's architecture" regarding its gpu and cpu. Wii U's 32mb of edram (it also has 3mb of extra to emulate Wii) was a choice that could have just as easily been a solution with a unified pool of gddr3 or 5.
Not according to the available info. The WiiU Espresso CPU is largely based on high-end POWERPC 750 tech like the cube/wii chips, but the edram was one of the IBM Watson POWER7 design feature enhancements AFAIK - despite it not being a POWER7 designed chip - although apparently has the POWER7 instruction set.
Compared to the Switch's TegraX1 T210, 4x Cortex-A57 (BIG core cluster) that is used when the Switch is docked(AFAIK), the Espresso has an extra 1MB of L2 cache, 3MB in total (512KB for the primary core - diving up the work - 2MB for the 2nd Core, and another 512KB for the third core) compared to the 2MB shared cache on the Cortex-A57.
From looking at the technical info available of both chips, the brawny POWER chip has far more advanced features for cache performance as you'd expect from downscaled IBM Server tech (as a by-product), which again explains a lot about why the Switch's improved GPU and additional RAM, alone, aren't enough to usurp the Wiiu in splitscreen multiplayer.
If you need the by-product argument made more convincing, tell me why can't you buy an Intel X299 motherboard with the ability to use a Pentium Gold CPU in it? The answer is: the exact same reason. The chipset is designed to compliment the CPU capabilities, so no point having quad channel memory interfaces, abundant PCIe lanes,etc if the CPU using the chipset lacks the design, cores and cache hierarchy to exploit those features.
In addition, Wii U CAN provide more bandwidth than switch, but only if a developer puts in the work to optimize for the eDRAM. Switch's single pool is twice as fast as Wii U's main pool with superior color compression to boot. But Mario kart 8 clearly got the most out of Wii U so I would not be shocked if switch dipped more in 4 player screen despite me not having personally witnessed these drops on Switch.
That's why MK8 i(and Splatoon2) are quite revealing, they are marque title that get the best out of both their consoles - with no expense spared on optimisation for either.