Uber infamously runs thousands of microservices because hundreds of engineers wanted independent deployment. Previously, small teams of 5-10 people generating 50 commits/20 pushes/10 PRs daily didn't need this modularity.

Today, a small team running 20-100 agents might generate 500 commits/200 pushes/100 PRs. Uber's approach may become the new normal. The more modular your code, the more agents you can run in parallel. Monoliths cause merge conflicts; microservices enable "embarrassingly parallel" work.

100+ agents must work independently or productivity turns net-negative. Splitting services used to be expensive—boilerplate, plumbing, CI config. Agents write all that now. Agents are also context-limited; modules fitting in the context window dramatically improve performance.

Your codebase's modularity determines how many coding agents you can run effectively, so it's worth designing for it from the beginning.