That's how it was maybe 100 years ago. Now PhD is just another bit of school work. Sometimes people manage to do really great PhD work, but most of the time it's pretty mediocre or straight garbage.

In some ways, people doing research now have it way more difficult than people of the past. They have hundreds of years worth of research to study before they are on top of things and making an original contribution that stands out among the huge amount of research that already exists is really hard. If we want to keep PhD as a proof of meaningful work, then we ought to lengthen the graduate studies considerably. How about a 10 year PhD program, at the end of which you can really say you have mastered the field?