I would have posted this in the Unpopular Opinions thread, but after typing it all up, I didn't think what I said would fit well with that thread, so I'm posting it on my profile underneath a spoiler, since it's gonna get a bit long.
Yes, the 'Vocaloid is dead' mantra again. I'm certain everyone is sick of other people beating that dead horse. But this time, I've been thinking if people have been saying that because of how the Western fandom behaves, and whether or not it's caused a negative feedback loop that's forced people to ditch Vocaloid.
This was inspired by a few posts elsewhere on here complaining about the behaviour of certain Western producers (I won't name anyone because I don't want to start drama here). Since the Western Vocaloid fandom is still smaller on average in terms of active producers and overall fandom, and said producers sometimes collaborate with each other, it definitely creates an impression of a small "elite" monopolising attention to themselves within the Western fandom. So whenever drama kicks off concerning popular Western producers, almost everyone in the Western fandom hears about it, and it spreads to here. The Japanese fandom, although it has its own problems with drama too, doesn't seem to have to deal with the same kind of bullshit the Western fandom has to put up with on a regular basis, because it's larger, more firmly established, and there are a lot of producers working in the Japanese scene to this day.
In fact, I think the problems with Western Vocaloid producers are part of the reason why Vocaloid hasn't become more "mainstream" (outside of artists like Porter Robinson) yet. Many Western producers unfortunately act unprofessional at times, which doesn't give any outsiders looking into the producer side of Vocaloid a good impression of the Western/English-speaking side. Of course, Robinson was already working in the music industry by the time he dropped 'Sad Machine', so him using Avanna didn't exactly pigeonhole him as a niche Vocaloid producer instead of a general EDM producer.
The more ordinary members of the Western fandom don't always help either. I think I've said before (or maybe someone else did and I'm misremembering) that Vocaloid has always had a reputation of being a "weeaboo" fandom. I'm old enough to remember the Golden V2/V3 years, and even back then, saying you were a Vocaloid fan was tantamount to admitting you were a weeaboo in some circles.
And believe me, I do remember a lot of the antics the more immature side of the Vocaloid fandom at the time would get up to. Mainly just stupid shipping wars and misinterpreting songs, but still. As the Western fandom developed a negative reputation, eventually some people either left the fandom out of embarassment, or just outgrew the fandom entirely and forgot about Vocaloid. Then these older fans are shocked to learn that Vocaloid is on V5 and the Cryptonloids are in the process of moving to an original engine. ^^;
TL;DR: The Western fandom probably "killed off" Vocaloid by negative association for other Westerners (mainly Western anime fans, but still).