Global state in general is bad practice well documented across tutorials and books about programming. Article's argument is that PHP avoids global state, but _SESSION hell and "MySQL table as global state" patterns demonstrate that programmers will always find a way to shoot themselves in the foot with global state :)

Also, IME even good PHP programmers suffer from the "MySQL-table-as-global-runtime-state" syndrome. And it's at least as bug-prone as storing global state in an ADT.