My first betta, Jimmy, was in such an arrangement. However, he got fed Betta food every single day; the cup that surrounded the plant had lots of big holes for air; I changed the water regularly; and he lived very happily for a couple of years (which is my understanding their average life span). SO, to say that all arrangments like this are cruel is not true.

Also my mom-in-law also had such a setup, and though her setup was a little different than mine, her fishy was very happy, and lived a couple of years too.