>>DashAn+(OP)
VSTs using iLok barely work on Windows/MacOS, I'd imagine their chances of working on Linux to be fairly slim, courtesy of the fact that the DRM is often larger than the plugin itself. Some manufacturers like U-HE have taken it upon themselves to start releasing Linux builds of their VSTs (albeit without support) and they seem to work really well from what I've tried.
So yeah, DRM is still an issue but the tides may be turning, especially now that the audio subsystem on Linux just got a massive rework.