I think relevant in this context is just poorly defined and probably unsuitable. Obsolete/obsolescent/outdated seems like a better fit for what people are trying to express.
Things that are thought of as obsolete one decade can end up quite desirable once again in another, usually because of a certain character of sound. Maybe 12 bit samplers fit into that category. Then there’s other gear that is too recent to have some kind of defining ‘lo-fi-ness’ about it, but old enough that its interface or connectivity has been superseded. Still doesn’t mean that you can’t make great stuff with it today if you happen to own such a device though.