Bill Zebub
“It’s probably Matt Mercer’s fault.”
Why should we expect players to want their groups to be disparate levels? What is the benefit to them?
I think the benefit is indirect. Not that one wants disparate levels for their own sake, but one might want to be able to bring in new players, or replace existing characters with new characters, without skipping levels.
EDIT: There's also some compelling narrative value, imo, to the trope of "seasoned adventurer guiding the newbies". That's easier to do with flatter power curves.