Harking back to an old post here, but this is a very uncharitable way of looking at it.
Handing out pregens to new players is not calling them dumb. It's not forcing them to go through a tedious process of preparation before they can actually play and find out if they like the game.
None of my friends would sit down for two hours to learn the rules of something. If you told them that was necessary they just wouldn't play. If I ever need to get someone to play a new game, we just sit down and play and they learn the rules as they go. For a game like DnD, if they got into it, then they'd look at the rulebooks and options afterwards. Which they'd understand easily because my friends aren't dumb. They just value their time.