Why did God not inform us of the true number of the People of the Cave, even though the purpose was to conceal them from the Romans?

We learned the number of the People of the Cave in an eloquent style, with an indication that there is no benefit in knowing their number. Ibn Kathir said that the verse contained etiquette in this regard and taught what is appropriate, for Allah Almighty recounted three sayings concerning them, weakening the first two sayings and remaining silent about the third, which indicated its correctness. Then He guided to the fact that knowing their number is of no avail, saying: (Say, "My Lord is most knowing of their number").