You get error messages if you get it wrong. Spot the bug in the below: // +build windows package my_pkg That's right, if you don't have a newline bet

You get error messages if you get it wrong. Spot the bug in the below: // +build windows package my_pkg That's right, if you don't have a newline between the build comment and the package, it gets ignored as a package doc comment, not a build tag. So that comment is treated as a comment, but if there's a newline it isn't. If we had a normal pragma, "go build" could error out instead, but we don't. Similarly, if you typo //go:embd file go build will ignore that as a comment. If it were '#embd', the tooling could error out with "unrecognized pragma". I think that's the main argument for not using comments.