Well, the Slayer is still pretty low. But the 2010 Enduro one makes sense. Like you're saying, small granny rings kind of necessitated more moderate anti-squat numbers if you're looking at the middle ring (i.e. comparing to a modern bike). A 22t ring on a modern bike would have a massive amount of AS, and consequently pedal kickback through the roof.
That's actually what drove me to 1x in the first place, back in the 9 speed days. My first gen Banshee Spitfire had so much pedal kickback that I couldn't stand climbing anything technical with it in the granny gear, and figured that if I wasn't going to use the 22t, I might as well lose it, the derailleur and the shifter, and run a proper DH chainguide, since clutch derailleurs and narrow wide chainrings weren't a thing yet.