You're not wrong about parental enablers, but those without that kind of support basically just end up as freeters. Cost of living is surprisingly low for a first-world country if you've got low standards, so life can be sustained by not many hours of a robotic low-wage job. The reality of sonkeigo/kenjougo phrasebook shit means that there's not much risk of authentic human interaction even in a public-facing role, so I think you'd be surprised at how many people who are technically employed resemble the classic hikkiNEET pathologies. I'd call it more of a worldview than a specific state strictly defined by employment status.