Good article but I think you've mixed a couple of scenarios here. One is when you're giving feedback on performance ("This graphic is horrible" vs "I see what you had in mind but can I offer an idea?"). Your points are right on the money.

The other is about leaving comments on posts. That's a different thing. (I read lots of political posts so that probably skews my thoughts on all this.)

If someone leaves a post that is:

Badly written

Badly sourced

Badly thought through

Rife with bullshit....

I'm gonna let 'em know about it in an uncordial way.

If the post is not guilty of these sins, I take a different approach, even when I don't agree with the author's premises.

But, yeah, being a jerk ALL the time is probably not the best way to make friends here.