A phalanx-based army is theoretically invincible. But the phalanx could never win on its own. It needs flank protection and the so called hammer, the heavy cavalry. And, most important, it needs an able commander who is capable of making the right decisions.

The maniple can do everything on its own. They are not very vulnerable to flanking. They don't need an able commander. They can even cope with an idiot as a commander. They don't need to be babysat.

The phalanx is theoretically superior, but practically inferior.

Does anybody know why the Makedonians abandoned their equestric traditions and couldn't field a heavy cavalry any more?