The ancient Greeks actually had many of the same problems as the Vikings would later have in regards to cavalry; cultural emphasis on infantry and seafaring, a geography ill-suited for raising horses or for that matter serious cavalry warfare, a comparative geographical isolation from the haunts of the better war-bred strains, and social factors. Most of those also feed each other - basic low quality of force-flesh encourages emphasis on infantry, enhancing the status of the social strata that said infantry is recruited from which in turn discourages developing a stronger cavalry arm. Decent war mounts are expensive to breed and train, after all, and have little other use; moreover, if the local lifestyle doesn't by itself encourage horsemanship and riding, considerable amounts of specialized training are required for the rider too.

AFAIK the Greeks never really picked up the Macedonian cavalry doctrine, not in the least due to their geographical considerations but also because what cavalry Philip and Alexander now did raise from Greece (they seem to have preferred Macedonians and Thessalians, and the Greek settlements in Asia Minor) was promptly shipped for service abroad and didn't have much influence locally.