Its specially ironic that the thing that benefits the most from it is Chansey: a Pokemon whose entire lore niche is a healer. I think the move deserves a nerf. Maybe, when a non-Poison type uses it, it inflicts regular poison instead of bad poison.
And if people feel that’s an overkill, a system could be put in place:
Non-Poison types apply the regular poison condition to the opponent, but if the move is used a second time on a Pokemon that’s regular poisoned, it converts into toxic poison.
Poison types get the superior toxic effect in the first go itself.
Yes Chansey line really should learn Purify