Again, this is where language breaks down. You are saying that each edition of the game is a separate game, but, for many people, this simply isn't true. Each edition is a different iteration of the same game. And that's why 4e became so problematic. Because for people like you or me, which judges each edition as a unique game, 4e wasn't an issue. To you or me, it's self evident that each edition is a separate game. I'll take a wild stab and guess that you didn't bother with converting 2e characters to 3e. Why would you? It's a new game, so, new characters.
However, there are those who don't follow this line of thinking. That each edition isn't a unique game. Each edition is simply the same game with some new ideas.