Oh, I don't know about that. I don't think items always just scale things up equally. I think some characters are definitely better with items. And some characters are much better only with CERTAIN items. And some characters are better at retrieving items.
Yes, some characters are better at retrieving items...but some characters I don't think are inherently better with items. Items act the same no matter who uses them.
Also I play with items for fun, but I never use ones that deal damage personally. I will avoid them like the plague. The fact of the matter is, I'm playing a fighting game, and I'd rather kill someone with my character, than kill someone with a random item. I understand I'm gimping myself in the environment, and maybe not playing to win fully, but I don't find any enjoyment in using a crutch to kill someone.
EDIT:
Also if items were allowed, the tier list would still be decided on the actual characters alone. Thats just the way it works.
Like, in 3S, its based on character strengths/weaknesses, and not including some "random" (to some extent) elements like parrying. Yeah, Hugo can be good if you have MAD PARRY SKILLS but not every Hugo has MAD PARRY SKILLS, so hes still low on the tier list.