Never got to Garrisons in the time I played WoW (though I've watched videos on it), were Garrisons a requirement or "basically a requirement"?
Also rewatching the video but I don't recall him saying you are forced to do the content makes it parasite, did you add that yourself? Edit: I do think you did, or you might have missed the point of why I made my post (I wasn't debating what the video said, I was saying people are already on different footing because the video isn't saying what people are talking about and it was clearly part of the OP's thought process.
"can be removed from the game and nothing would happen"
"sucks from other mechanics but doesn't add anything back" <- I feel this one is weird because, doesn't items count? Maybe they mean on a far more gameplay level.
Examples given like garrison and borrowed power.
"A parasitic design mechanic, aspect, system, or an update, that requires other systems to support it, taking time and resources from core resources but not ingratiating itself into those other systems"
"Trends that will eventually die, doesn't become an important part of the game."
So... just to be clear I'm not arguing what is or isn't a parasitic design, I'm saying what OP used as a starting point of conversation is counter to what people are saying. Like it seems like you are adding a qualification to what I just said, but that's not what the video said, so.. if we, you and I, are discussing it sure, but I was bringing up the video.
I'm not arguing for the video, just discussing people are already missing each other. In other words people are not agreeing on what the worse use is, from the very beginning. And that there are systems in FFXIV that OP's video would qualify for parasitic design.
Noting the end of my post making comment on content islands (basically what Eureka(s) are), are fine given some caveats, but that abandoned content is sometimes a bit sad (like squadrons). This is why I said "their" not my, if the video did discuss "required to" content then if you could timestamp link it because I watched it twice (while doing other tasks) and did not hear that once. If you want to add extra rules, be my guest, just realize you're not arguing me, as I was only conveying the video that started this.