Rystil Arden said:
Hey now, he was making a joke, as was Monte
Yes, and considering the debates on some topics in the past few months, very good jokes. (Indeed, I think Pramas and Monte both hammered the point home that game designers do need a good sense of humor and need not be at war with each other.

)
As for publishers disliking D20 or a specific rule set, I think that much of it is about subjective taste. I have to confess that most of the games I play are D20 based, but I sometimes enjoy other rules systems. (For example, at the last EN World Chicago Gameday, I played in a Mutants and Masterminds game, a Buffy game, and ran an event using aspects of the D&D 3.5 and Arcana Unearthed rules.) To me, a large part of what makes any game fun is how everyone at the gaming table interacts with each other.
I think that actively disliking a rule system and publishing products strikes me as strange. I think one problem that BiggusGeekus identified is important: many players are reluctant to master multiple rules systems. So, D20 does have an advantage in that many gamers already are familar with D&D. It is a shorter transition to M&M or AU than to GURPS for most players. Unless a new rules system or a game offers something very appealing to players, or has a tie in to something that they like (such as a television show), many D&D players seem to want to stick to D20 rules.
Also, if a publisher is unfamilar with the D20 rules or disdainful of the rules, it can show in the quality of the product.
Dragonlords of Melnibone by Chaosium was a product that tied into Michael Moorcock's Elric series and could have been very popular. However, the application of the rules was abysmal. I am not very familiar with Chaosium's products, but I thought that book was very poorly done -- despite good source materials and a fairly successful non D-20 Elric game. In the end, I think such products not only hurt the D20 market, but hurt the gaming industry as a whole. Plus, it can make the people at a company with a negative attitude seem petty. (No gamer, especially one considering a purchase, wants to feel that a publisher is looking down at them. So, hatred can be self-destructive.)