Yup. One. v. one missile units don't kill much other than the most lightly armoured opponents without a shield worth mentioning (aka: akontistai; sphedonetai etc.).

However having a couple of archer units or slinger units will ensure that the enemy unit gets attacked from multiple angles --> end of your Gaesatae. It's all in the effective deployment of your skimishers; and really when it comes to that the Gaesatae or Tindanotae simply don't cut it as your super unit.

One would rather have Hypaspistai for that job.