> Ardour supports only Linux VST (rarely used, unpopular format).
"Linux VST" and "Windows VST" are not plugin formats. "VST" is the format, "Windows" and "Linux" are platforms. Do you seriously expect a Linux app to run Windows plugins out-of-the box?
> Most of plugins use Windows VST, i.e. they are distributed as Windows-compatible DLL.
Yes, most (commerical) plugin companies only provide Windows and macOS binaries. But how is that Ardour's fault? You can run Ardour on Windows on macOS. If you really want to use Linux and you need to use Windows-only plugins, you can either run Ardour in Wine or use a plugin bridge such as yabridge.
On Linux, Ardour supports LADSPA, LV2, VST2 and VST3. Those are the most widely used plugin formats. What are you missing exactly?