SRD 5.1 doesn't include character creation rules or feats, so it's not even enough from just the PHB/DMG to play. But it's most of what you need, and the what's

SRD 5.1 doesn't include character creation rules or feats, so it's not even enough from just the PHB/DMG to play. But it's most of what you need, and the what's left can be easily replaced. The CC grant from the draft OGL 1.2 announcement was much less - it didn't include classes, spells, or creatures. Opening the entire SRD under CC BY makes cloning 5E trivial. I genuinely think this is WotC giving up on 5.5/One being open. They're going to double down on the Dungeon Master's Guild and its IP-friendly, Hasbro-owned license as the way to create and distribute fan content.