All good questions, Dread.
I'm under 40, and I just assume it was Barry coming in 2nd every time Climo won something.
And yeah, tough to know how much "value" people place on a single World's win. Barsby is an interesting case, because I feel like he also has a virality factor: has had a number of notable aces caught on film, which in my opinion raises his profile just from the number of extra clicks and youtube views he gets. Same for Philo with the albatross at BSF and that 400'+ ace at Maple Hill. And I'll throw Simon in the same category with his trick shot videos. (Also maybe a slight extra nod to Simon as a former distance record holder, not sure if that moves the needle or not.)
Now I'm not saying any of those guys crack the top 5, but when you start looking at 6-10 it might be worth considering those extra factors. Because we pretty quickly run out of guys that obviously qualify by the formula of "X World's + Y USDGC + Z other Majors and Tour Wins."
Although thinking through it, maybe the "virality" thing is more of a measure of the most famous disc golfers. Not sure if that necessarily equates to Greatest or not. And before all the geezers start complaining: yes, I understand that there's a massive recency bias associated with assigning any value to youtube views, because previous eras didn't have the same type of exposure.