Is diplomacy necessary?

to AmberSoler
I don't understand from your posts whether diplomacy is a useful or useless secondary skill, according to you. If it's useless, then give me an example of an ideal hero, in your opinion, with 8 useful secondary skills, and I'll try to replace one of them with diplomacy.
I personally consider diplomacy to be a kind of hidden, yet powerful skill.

I understand that AmberSoler meant that the importance of diplomacy depends on your goal and tactics for developing on the map – whether you are gathering creatures in your own (or not your own) city, or you are looking at who is on the map, and your goal is to gather as many neutral creatures as possible.
P.S. My opinion is that you should definitely try playing with diplomacy just to know what this skill is, and whether to take it further or not is up to you.