Well, let me be the first.
While I won't say there isn't an element of luck to success in webcomics, it's by no means the dominant factor. The quality of your product along with a decent marketing strategy built on top of a solid posting schedule has been the success of many comics, and the only element of luck is catching the right person/people's eyes at the right time.
Yes, there are bad webcomics out there, but they all have something tangible to offer, something for which their audience is looking. Success is a balance of how much people want to read your work and how effective you are at getting it in front of them. People who succeed in webcomics work damned hard at it, or at least the ones who succeed without working hard are the rare exception, and diminishing the results of that work by saying they were lucky is more than a little insulting. No, not everyone who works hard makes it, but not everyone who works hard has a product that people want to read. Hard work alone won't do it, and that's what the webcomics.com guys were talking about.
And as far as charging for comics, that's a pretty surefire way to get people not to read your comic. I can't speak for everyone else, but I do charge for my comic, through advertising and merchandise. You can't think of webcomics like a product, it's more like a service where you sell on the back end, like television and radio. There are television shows that charge money, yes, but their audiences are much much smaller and they have to bundle their services to sell them.
Cary, I sometimes scratch my head when I look at certain webcomics too and wonder how they got so popular, but I keep coming back to the idea that there must be something about it that catches readers. Plus, I think there's a level of lowered expectations, kinda like in your local music scene where a band who isn't so great and their bass player sucks but they still get gigs because there's just something about them.