The team with the Darius actually has a properly durable frontliner, making their comp actually better at teamfighting.
They also have a Thresh, who is a proper tank.
In fact, their overall scaling is just higher than yours.
Your only "tank" is a single Renekton, and maybe the Rakan.
You didn't have a teamfight comp due to the lack of any actual tank or juggernaut to soak up damage. You had 5 4 champions potentially good at teamfighting, yes, but you didn't have a teamfight comp. "Too many chefs in the kitchen", as the saying goes. You also probably had a bit of anti-synergy going on there, between Lee, Azir, and MF's ults.
You just lost early to a comp that would outscale you overall. The only champion truly strong in late-game you had was Azir, and I'm just going to assume he doesn't have the minimum 250 games on him to not be ass at him.