Is there some unspoken rule to not use Esuna/Leech?

[Genz]

I think a lot of healers just don't know and don't experiment enough. By that I mean, they try to esuna or leech something and it doesn't work, so they assume that's always the case.

^this
There is a rule in design, along the lines of : if two things have the same appearance, they must have the same function.
But status effects in FFXIV can have the same appearance (icon) but not the same function (some can be removed with esuna, and some can't, even if they share the same icon)

I think they actually bothered to make 2 different icons for poison (green icon = can be removed, purple = can't be removed), but for paralyze, silence, etc. you just have to guess.