I think Tommer's trying to say that one shouldn't just say, "Oh, well, Christine (or Stevie, or Lindsey, or Bob, or Peter, etc., etc.) isn't there, so the album is automatically lacking something."
Fleetwood Mac's lineup has been in a perpetual state of flux pretty much from the beginning (when Bob Brunning stood in for John McVie), so it's usually better to focus on who IS in the band at any given time, rather than bemoan the fact that someone else isn't.
