The arguments are well laid out by other responses, but the gist of it is that 90% of devs are wasting their time thinking about the details of infrastructure code, as it does not pertain to their skillset and it takes _years_ to master it.
You cannot get junior engineers contributing to infra, or most Semi-senior engineers either. You need a ton of upfront thinking about releases, policies, backouts, risk, etc.
And tbh, if you're thinking about those things it makes no sense that you also focus on user-facing features.
I wouldn't allow most engineers I know to touch infra code. It's just a very different skillset.