It doesn’t just matter what you look at! The eye calibrates with the signal from peripheral vision! Adding extra focal zones willy-nilly might cause very unexpected responses.
The stimulus to shorten the eye can happen accidentally with such glasses. The stimulus is hard to hit, but extremely powerful if hit – at least five times more powerful than the elongation stimulus in animal studies. So bifocals are able to randomly cause unrealistic signals to the eyes.
Caveat emptor. Everyone is responsible for their weird experiments. My dad has this problem of hyperopia+presbyopia+astigmatism, and to be honest, I don’t think he’s managing to improve. This combination is hard to fix.
And for those without presbyopia, the idea is just nonsense. Simply reducing plus power to add near strain all the time should do the job of fighting hyperopia just fine.