Atlantis was a great tool back in the day and still works well in most scenarios. The main issue with it is that it also takes on running the jobs (as in Terraform binary runs on the same VM it runs). Which makes it similar to Jenkins and other first-generation CI systems.

Companies that use Atlantis at scale (eg Lyft) felt the need to fork it and use a scalable compute backend instead, eg Temporal. At which point you've basically got a DIY in-house CI.

Our view is that it's best to keep matters separate. The CI part with compute, jobs, logs etc is a solved problem. What's unsolved for Terraform is state-aware logic when / how to run those jobs. It's all about the orchestrator really.