if Leica man doesn't advocate using filters you might ask him why Leitz manufactures them to go with their lenses;^)
Its not that he thinks all filters are always bad, he just criticises my practice of putting one on and never taking it off, using it as a 24/7/365 protection. I think even he would use one if he were taking a shot like Slade's rowing, above.
My feeling is that if I never take mine off, I'll never have to clean crud off the lens.
But of course I know that the filter isn't always needed, and I'm better off using it only when necessary. Maybe I'll just stop being such a sissy with my lens.