Compiler plugins are powerful, but still too limited. We can't change parsing rules with a compiler plugin, for example. There are also potential compatibility

Compiler plugins are powerful, but still too limited. We can't change parsing rules with a compiler plugin, for example. There are also potential compatibility issues with using some set of compiler plugins, and there's a performance penalty of implementing new features with plugins (which, by their very nature, are optional), rather than in the core compiler.