Why is the playerbase so mentally fragile now

[Zanarkand-Ronso]

This is a game where you can't help players improve..
because it is seen as a personal assault...and you risk getting banned.

Calling somebody bad, telling them they suck or to play a different Job/Class...is seen as aggressive and reductive. Its more of Insulting, then Helping someone improve.
Not saying you or everybody does this, but many people like to think and pretend this is being Helpful, or Giving Constructive Criticism, when its the exact opposite.

maybe examine how you offer it?

Exactly this.
Often Times its Delivery.
...But I wont pretend there arnt people who either ignore you, or simply dont want to be helped. At that point...at least you tried.