"When I was a child, I thought as a child," is easy to understand and perpetuate - but Paul also said, "When I became a man, I put away childish things."
I know it's cliche and too broadly quoted, but there really is great wisdom in the idea of milk before meat. The problem arises when it's time for meat and only milk is still being served. The lure and temptation is to focus on those who still need milk and call it a reasonable sacrifice for those who are ready to eat meat; the problem is that those who can eat meat need to eat meat to remain strong - or, to be more precise, to grow stronger.
Our ultimate goal isn't for everyone to be reasonably healthy - or even for nobody to be sickly; it's for everyone eventually to be incredibly strong.