Nietzsche’s famously made this claim in the introduction to his Beyond Good and Evil, but Origen said something similar in his response to the Celsus. Among Celsus’s numerous critiques was that Christianity appealed to the lower classes and that its ethics were derivative of philosophy. Celsus quoted the passage from the Timaeus—“It is a hard matter to find out the Maker and Father of this universe; and after having found Him, it is impossible to make Him known to all”—before declaring, “You perceive, then, how divine men seek after the way of truth, and how well Plato knew that it was impossible for all men to walk in it” (Against Celsus 7.42).
Plato’s truth wasn’t for everybody, Celsus was saying, nor was the path of virtue which was the central purpose of Platonism. Origen responded that Christ “was made flesh, in order that He might reveal to all men truths which, according to Plato, it would be impossible to make known to all men,” (7.42) and that “He has chosen the foolish things of this world — the simplest of Christians, who lead, however, a life of greater moderation and purity than many philosophers— to confound the wise” (7.44). Furthermore, said Origen, “He comes down to the weaker capacities of ignorant men, of simple women, of slaves, and, in short, of all those who from Jesus alone could have received that help for the better regulation of their lives which is supplied by his instructions in regard to the Divine Being, adapted to their wants and capacities” (7.41).
Thus Jesus made truth available to all classes whereas Celsus said that Plato knew that the truth “was impossible for all men to walk in it.” Which sort of sounds like Origen said that Christianity was Platonism for the masses.
The parable of the sower sounds like it’s making a similar claim. The key difference between the parable of the sower and the similar passages in the Phaedrus and Theages is that whereas Socrates would plant seeds in those who came to him to be taught, the sower cast his seeds far and wide. Platonism for the masses?
 In the Apology, Socrates says that he taught rich and poor without charging them, but in the last book of the Republic he says it’s best to choose to avoid being born into the lower classes (as it is to avoid being born into luxury) to choose a life most conducive to virtue.