True. But DM support content =/= rules bloat. Content a publisher can provide to DMs to help them run their own games without adding rules bloat:Plus, less rules bloat and more streamlined, simpler rules means it's easy to bring new players into the game. I'm experiencing this first hand DMing 5e.
Organizations (wizard's guilds, priestly orders, thieves' guilds, etc.)
Groups of rival adventurers
Merchant caravans and other groups encountered travelling
Castles and forts
Adventure hooks and summaries
Currently, WotC offers two approaches for DMs:
1) Level 1-20 mega-campaign presented in 256 page books of wall-to-wall text. All requiring extensive work, summaries, and aids to whip into a shape that is usable at the table.
2) Make up everything in your world from scratch. The campaign setting, factions, NPCs, geography, cities, lairs, temples, ruins, encounters, enemies, and adventures.
The first approach is made much more difficult than it needs to be due to the old-fashioned wall-of-text format. The second approach assumes DMs who like to run homebrew campaigns have the desire and the resources to make it all up from scratch.