You'd only be able to get through a single round of combat per game session. A single combat could last months. Everyone would save money because there would be no way to get through a single game let alone through multiple adventures.
Some part of me wants to like Phoenix Command but all of the other parts keep him rightfully locked away where he can't harm anyone.
One of three: Free League, Monte Cook or Goodman Games. Free League because they produce product that WOTC, and anyone else for that matter, struggle to meet and on a consistent basis. Monte Cook for similar reasons and because the level of creativity and innovation is second to none.
Goodman? Hands down the highest quality adventures with the most creative stable of designers and the coolest game for fantasy on the shelves. DCC is visually different, exciting and evocative of a style of fantasy game that no one makes anymore, if anyone ever did, but was very much present in the old artwork from TSR and in the novels, films and other media that inspired D&D without being Tolkienated. It isn't generic fantasy. It also includes everything that 3.x had in elegant mechanics that are simple and easy to understand. The entire adventure line up is pretty epic and comes the closest to emulating not just classic D&D but also Moorcock, Lieber, Vance and Wellman perfectly. While the adventures can hinge on a gimmick the designers make the gimmicks work. DCC 100 is a peak example of that along with The Chained Coffin and The One Who Watches from Below. Sailors on the Starless Sea is up there with Keep on the Borderlands or Village of Hommlet as the greatest starter adventure of any version of D&D. Goodman just "gets" what makes D&D great, something I think WOTC kind of slipped the last couple years and I am not talking about the nonsense most people complain about, I think WOTC is too slick, too clean in presentation. D&D needs some warts.
Honorable Mention: Necrotic Gnome for the same reasons as Goodman.
A shout for Pelgrane Press. I’m a fan of the GUMSHOE system and they produce a great range of games, covering genres from Lovecraftian horror to spies vs vampires to Swords and Sorcery. Plus, they’ve created several games for GM and single player. And their books are uniformly gorgeous.
Also a spot for Flatland Games, whose Beyond the Wall, Grizzled Adventures and Through Sunken Lands are all F20 delights.