All this is true, even though I'd still hold that they don't have works that stand with the best of the recognized greats' works.
But again, some of these composers have works that are firmly in the general repertoire — Biber's Mystery Sonatas, Marais' amazing suites, the Leclair 2-violin sonatas — and others are real mainstays of early-music performances. I'd say they have the approval of that long-term taste filter that we were talking about. (I'd quibble about the long-term staying power of Busoni, but the point still stands.)