Some armchair philosophy.
Many have asked: "Why is it important?"
Diving, after all, is SUPPOSED to be a non-competitive sport. In truth though, humans are inherently competitive creatures. Just ask a Neanderthal! Added to that, Western culture has certainly esteemed "healthy competition" since it's earliest origins.
One way to compare might be through certification levels. I think we all know what a crock those are. Today's DM might have been last months aquaphobic. While there is a linear progression to certs that implies advancement such is not always the case.
Next, one might count number of dives. While this is probably much more indicative of experience, there are many variables that cloud a direct correlation to the diver's actual skills: water temp/exposure protection, depth, guided v. independant dives, duration, visibility, etc. This provides a very arguable comparison.
A somewhat more empirical measurement is depth. Two common questions from non-divers are: "What do you see," "and how deep do you go?" The latter is more easily assimilated into one's understanding. We understand on an intuitive level that deep equals dangerous, therefore to have gone and returned must make one better. Further, depth is represented by number (especially impressive when displayed in feet) and is therefore easily compared.
I've seen posts like this before, and I'm not trying to bash anyone for anything. Indeed I might be said to be defending such posts through examining the reasoning behind this persistent question.
I have been to well over 30,000 mm on open circuit with air and returned to tell the tale. I enjoy wrecks but they tend to be deep. I have taken the appropriate training, and try to maintain my experience at depth in different conditions. I am not super diver. Just thought I'd offer my answer to the ops question since I decided to preach.