The tools (mostly) all start out simple, as you described. Then they start to get traction and users. More users equals more diverse use cases and feature requests. Each individual request makes sense, for that group of users, and is implemented. Slowly the software grows in complexity, until you have Hugo etc... Then people say it's too complex and start over - and it all happens again.
This applies to all software - and most other things that humans make that have large numbers of users, like governments, countries, or other systems.