A pattern we're seeing increasingly commonly are Platform Engineering teams doing the bulk of the work, including all the fundamentals, guidelines, safety railing, and conventions, while Software Engineers only use those, or write their own simple service-specific Terraform Stacks which however extensively use modules developed by the former.
This does also seem like the sweet spot to me, where most of the Terraform code (and especially the advanced Terraform bits) is handled by a team that's specialized for it. If you don't have a Platform Engineering team, or one that is playing its role (even if its called DevOps or Ops or SRE) in even a medium company, you'll probably start having as many approaches to your infrastructure as there are teams, complexity will explode, and implementation/verification of compliance requirements will be a chore. Just a few people responsible for handling this will yield huge benefits.
And yes, I can wholeheartedly recommend Spacelift if you're trying to scale Terraform usage across people and teams - and not just because I work there.
Disclaimer: Opinions are my own.
[0]: https://spacelift.io