Fully guaranteed deals are only any different than non-guaranteed if you're going to release the guy. Having that flexibility after one or two years is huge for the team for most players, but for QBs where even the salary that wasn't guaranteed at signing becomes guaranteed 18 months ahead of time, its a lot less of a factor. Everyone else, you release the guy and you don't have to pay them. QB deals you release the guy and you still gotta pay them for the coming season in most cases on the big deals we've seen recently. The difference is you take on about one APY worth of risk, give or take depending on the structure, for a fully guaranteed deal compared to a typical QB contract where the 2024 salary would become guaranteed this March a few days into when the 2023 league year begins.
The Browns can release Watson, they'd just have to pay him everything left on the deal. So if they release him now, they're basically paying him for 4 seasons they didn't get. If they release him after 2023, they eat 3 years...after 2025, they eat 1 year.
The Cardinals guaranteed a bit more than two years APY worth of Murray's deal at signing, and then each year we move forward another year out becomes guaranteed. They can release him now and only have to eat 3 years of money (compared to 4 for Watson). If they wait and release him after next year, they eat the equivalent of 2 years of money (compared to 3 for Watson).
So its like 20% riskier, if we're looking at 5-year contracts which seems to be the norm. Its not as big of a difference as $235M guaranteed at signing vs $103M guaranteed at signing would indicate.