Ballet was invented in the the 1500s, as one can imagine it was largely a mans world - or rather his dance floor.
Ballet was created by men for men, and since we still we call ballet "classical dance", the rules haven't changed and women simply adapted.
When watching a male dancer one can easily see that ballet was meant for them, their ability to seemingly pause gravity in mid-air for their spectacular jumps and turns that seem to do circles around the laws of physics is something most men are simply more naturally adjusted for.
Men typically do not go onto pointe but rather assists the ladies, and instead of lifting weights they lift women - it is a blend of strength, endurance, flexibility and grace. To master this is the ultimate achievement.
"No man has the right to be an armature in the matter of physical training. It is a shame for a man to grow old without seeing the beauty and strength of which his body is capable." ~ Socrates