I wonder if we're all talking (or thinking) about the same thing. IIRC my molding had an 'L' shaped flange under the chrome "molding part' that grabbed the windshield. The moldings people seem to be showing are flat. Does flat molding seal properly?
Yes the stock molding has a flange but I'm not sure how it would help with sealing the windscreen. I think the seal is made with the sealant (can't remember what it's called at the moment, but the black sticky goop). The stock molding might even hinder a good seal. Others seem to have left it off completely.
In my original post I was showing an alternative that worked for me. The stock molding on my car looked like crap and couldn't be replaced without removing the windscreen (and risking breaking it in the process). I installed the flat alternative without removing the windscreen, it was inexpensive, I think it turned out well, and it still looks good after three years (not sure how long it will last, but not sure how long the original molding lasted).