You only have so much traction to accelerate, brake, and steer. Sharing them on the same wheels seems objectively worse at the limits to me, except in the sense that every car is all wheel stop.
I think some of the safety issues associated to RWD were problems of the days where they were more common. Trucks need weight in the back, we know that, and winter tires are way better now.
You have to learn how the car handles when it's not an emergency to know what to do in a panic. I toss every car I own around in a snowy parking lot at least once so I know what it'll do. This seems insane to a lot of people I've talked to.
That said, I think understeer is safer and more predictable in most situations for people who use their cars as a transportation appliance. You point and shoot, so to speak. Most people aren't driving at the limits.
Strictly speaking, if your car is out of control, you're driving past the limits. The whole point of the parking lot exercise is to learn where the limit is. I drive like a granny, but prepare for the worst. And I've learned over the years to avoid the first day of snow in a season.
You've still got one control working in the rear: brakes. The understeer characteristics of a FWD car are very easy and intuitive to recover from. If someone can't manage traction in an FWD understeer condition, they almost certainly lack the skills to manage oversteer.
This might be true when discussing snap over-steer and throttle induced under-steer on a track but is a complete lie for snow driving where most drivers will just keep steering harder in response to under-steer which is not productive and you don't have enough traction for lifting and braking to induce much extra weight on the front.
That's my point. Make the wrong correction in RWD car and you end up oversteering beyond 90 degrees in an unrecoverable spin. The failure modes of FWD understeer in the snow are all recoverable.
You're making one of those textbook correct but reality wrong statements that clipboard warriors love.
Sure, you can recover from under-steer but if you're already doing the wrong thing and pointing the wheel where you want the car to go you almost certainly won't.
With over-steer if you do the "natural" thing and steer the wheels toward where you want the car to point at least you have a chance. Sure many people might flub it but that's a heck of a lot better than the "no chance" you get if you react the same way to under-steer. Also, if you do over-correct the over-correction may very well not be as severe as the initial over-steer giving you a better chance to get it right the second time.
Sure, under-steer is theoretically recoverable and with over-steer you can theoretically spin or slide backwards but in reality in "on the street" situations (i.e. not what you see someone doing on an old taxiway in a training video) 99.9% of the time you'll have hit something long before either happens.
That is the understated safety factor of understeer, but people prefer to think in terms of never doing mistakes instead that in terms of overall safety
The trick, in my experience, is to learn how to get into a tailspin and do donuts. Unplowed parking lots are best for this. When you're familiar enough with the vehicle to do controlled tricks, you're just about prepared for an emergency. I've never owned a FWD car through a snowy winter; it's really down to what you're experienced with.