I suspect that a lot of the non-linking behaviour comes from the subtle cultural indoctrination we’ve been living with for centuries now (since the advent of copyright) that a musician who is influenced by others is a lesser musician (by exposing themselves to considerable risk of being less original).
Copyright effectively says that the only works worthy of the public’s attention and their reward are works that are wholly original – any derivative work is a trespass upon the work of the ‘original’ creator and warrants their consent or veto.
A musician who links to another is admitting exposure to that other musician (unless perhaps in a wholly different genre that they doubt they’d ever wish to explore in the future).
Perhaps when copyright is abolished, and its spurious stigma of ideological theft dissipates, all musicians can come out of their closets and embrace each other and their works as naturally inspirational or influential to a greater or lesser extent.
It’s the same with authors today who fear to reveal what books they’ve read or may have used as references for fear of copyright infringement (or even accusations thereof) – far better to pretend to be unread with any apparent similarity to be pure coincidental.