It does use
The point is not to not use stacks.
Also, inb4 pratt parser.
However, since all AutoIt statements have signal tokens (e.g. there is some unique token at the start of every statement: switch, select, while, for, do, func...), A predictive parser is probably the right way to go. Pratt's is more suited to maths expressions, its main strength being resolving ambiguity easily, allowing it to be easily extended.
Reading through my textbook now, most of the algorithms are stack and table driven (or recursive descent). I definitely think you could do better than having two separate parsers though. That does not make much sense.