You seem to be insisting that only the person using a term gets a say in what it means, and that they need give no thought to what the term means to those reading or hearing the term, or its broader implications or any confusion it might cause.
That's a bit like claiming someone can call people "racists" (because they've decided that it means "person who drives", on the basis that racing a car involves driving it, so anyone who drives is doing what race-car drivers do, and that racist is to racing as horticulturalist is to horticulture), and that anyone who objects to being called a "racist" is the one in the wrong. After all, the person using the word means something completely harmless by it and for them there's no implication or insinuation of anything else, right?
If one gets to say that words mean whatever one wants when one uses them, and need to give any thought or concern to what the words mean to anyone else, then green ratchet austria totebag goofus garbunkle.
"Ritual" is a perfect parallel for what's going on with "collaborative storytelling".
"Ritual" strongly implies something done for symbolic or emotional reasons, even when it is devoid of objective efficacy. To say that someone is "engaged in a ritual" when they brush their teeth or take a shower is to say that they're doing so for symbolic or emotional reasons, rather than for practical effect, which is not a universally true assertion.
http://www.dictionary.com/browse/ritual
Note the common thread of all but one of the listed meanings. Note that the origin of the word is in the same Latin root as a "religious rite".
And what's not indicated there is that the use of the word "ritual" to mean "any practice or pattern of behavior regularly performed in a set manner" comes largely out of a dubious academic assertion that humans do repeated things (like brush their teeth or shower or eat at the same time every day) for symbolic or emotional reasons, or reasons of tradition, rather than for practical reasons. (IDK, maybe that's true of other people, but if it didn't do any good or if I'd wake up with fresh breath and a healthy mouth every day without brushing, I wouldn't waste time on it... and I have zero use for ritual or ceremony of any kind.)
To say that someone's behavior is "ritual" when they're doing it for purely practical reasons is to imply something that is not true or useful about their reasons for doing it.
Similarly, the assertion that RPGs are inherently "collaborative storytelling" came specifically and deliberately out of an attempt to elevate one approach to gaming and denigrate other approaches. It causes confusion both externally with non-RPG activities and internally between wildly different reasons for and methods of playing RPGs and related similar games. You cannot escape those implications of the term when you use it -- the term will never leave that baggage behind, ever.
You're using a term for all RPG gaming that only says something true and useful about some RPG gaming. I do not care and will never care if the term can be considered technically applicable via pedantic analysis of all possible meanings of the individual words that make it up. Every time someone says "all RPGs are collective storytelling", I will object and I will explain why they are wrong.