Yes! And in many ways, this is part of what confuses me, though maybe I'm overthinking.

Here's how I landed here. Puzzle #1: why did my original bolt break so easily if there shouldn't be any issue regarding re-use of bolts (I wasn't yet up to 38 NM/28 FTLBS when it broke, and was amazed at how easily the stub spun out). Possible solution to 1: the bolt was a stretch bolt that was stretched to capacity, and so shouldn't have been re-used. But this leads to puzzle #2: why does neither the FSM, nor any tutorial I've read about valve stem seal replacement or rocker arm removal advise caution regarding this? Instead they all say just to put the damn bolts back in and torque to spec. Possible solution to 2: there are two varieties of bolt MB used here, a stretch variety and a non-stretch. The FSM and most tutorials cover the non-stretch. This would also explain the multiple part numbers. And according to the FSM note I attached earlier, it looks like this is just what MB did with head bolts generally, only they made sure to note it, and perhaps didn't do so with the rocker assembly ones?

So what does this analysis overlook?