Fair enough.
Although I don't think the cars in question would have wet traction acceleration issues. Which would be my real fear: losing grip in the rain, once up to speed. Once above a certain depth, the traction should be "good enough". At least until past legal speeds with deep standing water on the road... in which case, slowing down would be advised, regardless of tire depth, and doubly so if the driver "knows" they have some sketchy tire depth.
Snow is different. Pushing past 30mph or so in the snow is a fools errand, and best done with caution. We all do it, of course: but no one is surprised when it goes bad--and if one had such wildly disparate tire depths, they likely wouldn't be pushing that speed in the first place. ['cept it wouldn't be 5 vs 8, as 5/32's is about bald for a snow tire. Numbers made up for comparison purposes.]
I've only ever had one car with wet traction issues, and that was due to bad tire choice--I noticed that line of tires went away very quickly. Nothing else has had enough power to spin a tire on wet pavement, and even that car wouldn't, once a better set of tires was procured.