I do not feel that my answer deserves to be negatively criticized, either for tone or content. Perhaps before getting your shorts in a twist, you might re-read it.
That said, and this is directed to existing members of this forum, I refuse to perpetuate wrong information, when perfectly good correct information is available. Yes, I feel strongly about right and wrong. I'm just an old-fashioned guy, I guess.
The RJ designation refers to the WIRING SCHEME of the plug/connector combination, not the PHYSICAL ATTRIBUTES of the hardware. Our RJ problem is similar to the way that "RS232" (a wiring standard) has become conflated with "D-connector" (a specific form-factor).
Your examples are irrelevant. You cite trademarks that have, to the chagrin of the original owners who did not protect them, crossed over into the public domain. Since there never was a trademark called RJ9 in real life, it can't have become "common usage." It is a fiction.
"Common usage" ??? Then please explain what an "RJ10" or an "RJ22" is. Should we just keep adding more fictitious RJ numbers for handset jacks, until we run out of numbers?
Speaking of mis-information that is our responsibility, as experts, to correct, how about "handset" for telephone set, or "PBX" for key system, or "bell" for ringer, or "speaker" for receiver unit, or "cable" for wire (and vice-versa) or "rotary" for dial, or ...
