It's more a airline thing. You will find direct flights to all major cities it just won't be with all major airlines.One thing that while booking a trip which surprises me is that there are so many flights that you'd think would be an easy one, but require a connection instead to get from place to place.
My trip just gone had all direct flights but I wasn't trying to save every cent. On a previous trip money was tighter so saving on multiple flights was a option I took that meant flying with a connection.