Presumably, this guy's never seen $_SESSION hell: enormous amounts of state stashed in a single super-global associative array that persists between sessions [1].
In addition to $_SESSION hell, lots of custom PHP applications end up with extremely complex and convoluted MySQL tables dedicated to storing what would typically be global application state.
Both of these can lead to difficult-to-debug performance issues, race conditions, and especially security vulnerabilities.
Global state is going to happen, so languages/libraries should provide mechanisms that make it easy to state and enforce strict invariants on reads and writes to global state.