I think this point your making may actually prove the opposite. Charles Barkley was so good that I actually forgot he hadn't won a championship. I'd just assumed he had, such was the weight of his skill in my mind.
Still, I won't begrudge you for having a different opinion on what makes a player one of the top all-time. If championships are that heavy in your weighting, that's for your to decide. For me they're a team thing, not an individual thing, so our all-time lists probably differ slightly. That's fine, in fact difference of opinion is the only thing that makes such a discussion interesting.