I was reading Hatcher's Notebook about action and cartridge strength. Hatcher states that rimmed cartridges were stronger than rimless because that the case head was completely supported around its circumference. The problem is the area of the cartridge that is exposed and unsupported due to the extractor/groove radius.
It's true that the extractor groove radius does "leave some part of the actual cartridge case wall hanging out in the air". That's a direct quote from the book. He further states: "a rimmed case does not have this weakness. The case enters right up to the rim and there is little chance for the cartridge to fail at the head".
Hatcher said the reason a weak action (compared to Mauser's and the like) survived without blowing up was because it used a rimmed cartridge. This sounds like action strength and cartridge strength are being confused but there's a lot more to the chapter that better explains it.
The context of this was in relation to extreme over pressure scenarios. He used proof loads of 75,000 psi and some up to 120,000!
It's true, that today we don't seem to have any problems with rimless rifle cases blowing out. If you were to build a bolt action rifle for ultimate strength...wouldn't you build it for a rimmed cartridge? Forget any feeding issues. Maybe you use a Mannlicher rotary magazine to deal with this.
Assuming we are only dealing with bolt actions....It seems that a rimmed case, with a fully recessed bolt face that completely surrounds the rim, would make the strongest possible combination. Do you folks agree with this?