Envy is a natural human emotions and all emotions when expressed calmly, always lead to positive outcomes. No emotion is negative, in and of itself, and therefore no emotion should be feared and oppressed: for it is oppression that leads to a pouring forth of emotions as negative, hateful actions.
His post ended with "amazing" it was very positive and he did not deserve to be called narrow minded and Steemit is at no risk of being corrupted by him or anyone like him. So, yes expressing all emotions should be encouraged, unchecked, for that is the basis of art, but that is subtly different from inciting people to be envious or hateful. I guess you need to learn to listen to the subtext of what is said.
I am unfamiliar with the feminism person and I do not see the relevance of mentioning her here because if she is like the op, then she's fine and if she isn't like the op, then she's not relevant to this discussion.

Do you really think that your words weren't insulting and rude because you paid lip service to the words, "please" and "respectful"?
"please let me respectfully say that you are....being narrow-minded"
What about if someone said to you, (and I'm being purposely outrageous here to prove a point), "please let me respectfully say that you should fuck right off because you are a stupid cunt" ?
I call it, "stealth bullying" because it is a subtle method of belittling people, maybe you didn't even realise that you were doing it, it may just be a habit that you've picked up without realising. Of course it isn't as bad as just plain, old rudeness, I'll grant you that, but it is still aggressive and demeaning.