That's not true at all, There is indeed a "self", and nearly all functions are executed in a context with a valid self. Additionally, there are plenty of nodes

That's not true at all, There is indeed a "self", and nearly all functions are executed in a context with a valid self. Additionally, there are plenty of nodes such as "Get Player Controller by index" which allows the user to access and modify global state. There is a "pure" option to check on a particular function, but the language itself makes no checks as to the validity of this, it just allows the execution engine to make assumptions.