That's why I'm asking for a more precise definition.
To me, it seems kinda hard to discuss the implications of something, when you don't understand what it is - or when the people discussing it, have incompatible ideas of what it is.
For example, by the arguments of this article right here, AR/VR is not a requirement for a metaverse (otherwise the current internet could not be a metaverse, right?).
According to the keynotes/talks of Facebook and John Carmack, VR seems to be the most central ingredient though.
Raph Koster seems to rather agree with the notion that VR/AR is not required. It only has to be multiple virtual worlds that (at least some of which) can interact with the real world somehow.
As another example, Raph Koster thinks, that there must be many virtual worlds in a metaverse, and that this virtual worlds must be able to be significantly different from each other - visually and mechanically.
Facebook seems to think that having just one single virtual worlds (Facebook's own VR-world) is kinda enough to create a metaverse.
This article right here implies that no virtual world is required at all - as the internet doesn't qualify.
As a third example, both Facebook and Koster seem to agree, that it is important that a user in the metaverse be represented through some sort of Avatar. They seemingly disagree on what constitutes an Avatar though - Facebook's ideas imply a full 3D VR Avatar - while Koster counts MUDs as virtual worlds, where you get nothing but a handle (username) and maybe a small "description" text-box.
This article seems to deny even that notion, since in the internet you are just a more or less random IP-address. You can have all sorts of Avatars on various places on the internet - from usernames to profile images to fully customizable 2D or 3D-models. But all of those are separate and siloed.
And that's just the first few examples that came to mind - there's a lot more contradictions like these.