Why are people calling the NM train "parasitic"?

[Granyala]

Because it is. For 3/4 of your leveling experience the system does not allow you to make any meaningful contribution barring resurrecting the dead.
So yeah: we have to be a parasite until we get to a level where we can actually make a dent and help.

It's not a problem mechanics wise, but it feels shit standing there, being damned to AFK b/c you cannot help.

Literally the only thing that changes for an underleveled healer is that they have to make sure not to be hit by ANYTHING because even a brief graze by a trash mob will 1-shot.

Yup, and since no one can be arsed to tank adds or randomly pulled trash mobs YOU will get the aggro if you are stupid enough to heal. So while our healing is not affected, it's still useless most of the time because the moment we cast them, we get gangraped by adds.