No, Linux doesn’t have “much better hardware support than Windows”. It is harder to set up and maintain, so it’s worse. It doesn’t matter if you can make it work. It doesn’t matter if you can make things work that don’t work on Windows. If I plug it in and it doesn’t go, then it’s worse.
Meanwhile all five generations of GCN are varying levels of abandoned officially on Windows while Mesa supports AMD cards going back to GCN1, and even more recently started to enable AMDGPU support by default on GCN1 and 2.
But yeah, as for Windows having better support, GCN1-3 are long since buried officially for that OS, and Polaris and Vega have a foot in the grave at this point as they're curtailed to security updates only officially on Windows, contrasted against Mesa still actively supporting that older hardware. Also, can't emulate RT on RX 5000-series and older cards on Windows, while you can on Linux.
And yes, I'm aware of R.ID modded drivers for those older cards in Windows, but for this context, I'm only counting official driver support.