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

[RyuDragnier]

That's not really fair. While a healer might choose not to do it, oftentimes they are making multiple choices at once and your paralysis is low priority.

Healer choices often look like:

1. Keep the tank up.
2. Keep the dps who is at 10% life up.
3. Avoid one shot AOE.
4. Get rid of your non-lethal status debuff

You better believe that your debuff is not going to be dispelled until the very end, if at all....

Depends on the dungeon and HP. I've seen far too many healers who refuse to Leeches/Esuna when everybody is at a high HP amount. I'm pretty sure those are the moments he's referring to.