Lol @ the people suggesting AI Dungeon as an example of good procedural gameplay. Really? The only example of good procedural gameplay today is Dwarf Fortress.
That doesn't seem right. There are innumerable roguelike games with great procedural gameplay, not to mention stuff like Minecraft, or rogue-lites like FTL; if anything, I would put Dwarf Fortress toward the low end in terms of the quality of its gameplay, though of course at the high end of its ambition. Even then, I'm not sure its gameplay is better than Rim World or Prison Architect or other games inspired by it.
That said, I agree with the point re: AI Dungeon. I don't think AI Dungeon even has gameplay. It's a very interesting project, but it's much more like a narrative game where the player drives the action. Sometimes you get a bad result in the sense that the AI screws stuff up, but the key elements of what I consider gameplay (rules and outcomes) are absent from it. In a MUD, if you type in "kill orc," it initiates actual gameplay. In AI Dungeon, if you type in "kill orc," you kill the orc and it writes a narrative piece about it, sometimes amusingly inventive, sometimes idiotic. AI Dungeon may show the potential for an AI director who can actually provide the narrative substance that players add in when they tell stories based on what happened in Dwarf Fortress; but I'm not sure it actually shows the potential to make gameplay.