1) that's not something most AWD car owners worry about - it's a form of maintenance diligence like tire rotations and checking their oil every fuel stop that few drivers bother with, without serious consequence.

2) That clearly only applies when all the wheeels are connected through limited slip differentials. When the front and rear axles are run by independent electric motors with electronic power/brake distribution and regenerative braking feedback systems? you may need to revisit your mechanical assumptions.

I've owned two Subarus, and this has never been recommended to me, even from the dealer.

I'm surprised that hasn't been recommended. It's hard on the AWD system, and Subaru recommends it: https://www.subaru.com/owners/resource-center/vehicle-care-t...

Partially valid: having different diameter tires can lead to lash or noise in the drivetrain, but that extra noise/stress depends on the diameter difference. You're not going to HAVE to buy all new tires if you have a blowout and need a new one. Your drivetrain won't explode if you put on a new tire with three used ones. Decent tire shops are able to shave tires to match the rest of the set if there's a big difference.

Also, I don't see anything physically connecting the front and rear tires - this is where much of the drivetrain wear comes from on AWD/4WD vehicles.

If that's the only downside, sign me up! I live in the northeast where having AWD is a basic necessity unless you like not getting out of the house most of the winter. Also, most people don't blow out tires that frequently to really worry about this. In fact, if you get new tires, you can often get pretty cheap warranty/insurance against this.