A difficult topic to be sure as so much depends on context - for example rebuking "some people" for a personalized interpretation of the extent & intensity of their word usage & meaning within an unknown, unstated "disagreement" presumes some assumptions of it's own.
I'd not fret the dubious use of a slang term quite to this extent. Both language & the people who use it are dynamic, words and their meanings change not only with time but by subject and social group - generally & most particularly with slang, it's majority rule through common usage in context regardless of any original word origin or meaning.
A classic example would be noob & newb, often used interchangeably "newb" is simply a novice whereas "noob" is derogatorily used to state mental inferiority, inferring an inability or refusal to learn.
...but few know & no one cares about those distinctions anymore, common usage has blurred the meanings to contextual only, without that context the intended meaning cannot be known. Without the intent or meaning, how can it's depth or intensity be judged?
One of the interesting things about this "hater" example is exactly it's comparative intensity in common usage - regardless of what may be a personal objection, it's most often used as a shallow dismissive of an individual or group's shallow dismissiveness, eg;
Chevy Guy: "Fords suck."
Ford Guy: "Chevys suck."
Bike Guy:"Don't be haters, cars suck."
...at which point the disagreement is usually expounded on, if there's any significant depth to it.
This makes any out of context reactionary offense to just the word "hater" questionable to say the least, as what it seems to be here are vague insinuations in protest of a vague deprecatory comments in response to what was likely vague dismissals in the first place. In this instance a heated response to a casual dismissal of a casual dismissal.
By in large the points of contention here are meaning & intent, that such is unknowable without "getting to know that person first" - in that I wholeheartedly agree, up to and including what "they" may have meant by a word someone used rather than just one's own reaction to it. Be wary... for if the meaning you have ascribed to a word that someone else has used supersedes their intention or understanding of it, any offense you are subject to above & beyond their intent or understanding is your own - you may well be insulting yourself with little more then presumption. In haste, you may become what you decry.
The empty dismissal "hater" undermines itself with it's lack of coherent substantiation, as does the unequivocal rejection of any who may use the term - the protest becomes null.
On this international forum comprised of members of all ages & literacy levels in particular - it's not what you say but how you say it, not the words used but what may be meant.
Anything else would be chaos indeed.
