3 ms·

Possible reason: to distinguish the list from an "or" list.

• Avshalom 11y ago
  It was more of a rhetorical question from 6-8 year old me. Yeah, though, and certainly there's other reasons, like distinguishing it from a bunch of dependent clauses. That we elide "and"s when speaking a list is of course a point in favor of the comma being a separator not a replacement too. At the end of the day it's English; we just do what feels good.