I would say that "most people" limit to the races in the PHB which includes dragonborn, tieflings, half-orcs and gnomes, if that's even true. I have no clue since for the most party I don't get to participate in many other people's home campaigns. When I do play it's either with my wife as DM (we share a campaign world) or I do AL which is everything.
But the best numbers we have seem to indicate that the races from the PHB are the most popular, which is hardly surprising. A lot of people probably never purchase anything else. So to a certain degree it's a chicken and the egg scenario, but it's also based on customer demand.
Could I create a world with no elves or dwarves? Sure. I just don't think it would make much difference after the new and shiny wore off after a few sessions. We'd still be playing D&D with races that were stand-ins for aspects of humanity with slightly unique abilities.