Check again, I'm not defending this "infinite HP on miss" stuff. But neither am I assuming all minions have just 1 HP.
I don't have the link, but you can check around that normal monsters with more than a dozen HP have become minions to higher-level PCs. Things could have changed, but Keith Baker reported that any monster can become a minion depending on the difference between its level and the PC's, and the philosophy is that you don't want to keep track of HP. If the stats bring "HP: 1" for all minions, than this hit/miss discussion is moot, and the fact remains that is a construct to represent the intended game result. Its not that you get to level 30 and suddenly all bone devils have 1 HP, it's just that the multiple HP they DO have is pointless against the PCs.