I assume the majority of the aversion to checking co-planar has more to do with trying to keep brand new users from actually adjusting the lower wheel factory setting (which is likely very wise to have them avoid) more than anything else.
To me, it makes sense to check and assure that there is minimal axial load on the bearings and also that the saw is not applying a twist to the blade.
I don't recall exactly how I did this, but I believe it involved clamping a straight edge across each wheel and bridging a level across both straight edges, when they are parallel on x and y axis, but I may have done it with two levels and checked across both of them to sight them like a set of winding sticks.
This is perhaps best left for a saw that has been restored or repaired, or is running horribly, rather than something that is running well. My saw's bearings died very early so to me it was worth checking and I discovered them to be out of alignment enough that I decided to improve the settings.
For guides, I don't think it has been made explicit, but in my experience having them utilize the front portion of the guide (so that they can rotate if the saw blade touches them) has been best, Seems like that is in agreement with what you wrote.
Bumbling forward into the unknown.