This article reads like more of an ad than anything else.

> Environment variables only deliver values

Yes, the problem .env files try to solve is having "environment variables" be injectable from a file so that different applications can have different environment variables by default.

> A string is not a schema

Yes, input validation is an application concern. The application should know what these values represent / how to parse them and error if they're invalid.

I could go on, but the article is all about trying to use a hammer as a screwdriver and complaining that the hammer doesnt work.