Supportive tank items are pretty good alternatives to pure tank items
Support build: 1700hp | 120ar | 120mr - 10,700g
60ar 30mr
30ar 60mr
400hp 60ar
450hp (+255-350hp)
500hp
Tank build: 1650hp | 180ar | 55mr - 13,200g
425hp 60ar
90ar
350hp 60ar
450hp 55mr
425hp 60ar
Not a lot of difference in stats between the more costly tank items and the supportive tank items. It's kinda lame. I think we should increase resistances for pure tank items cause the extra survivability you gain from them has rarely been noticeable. If you ever get caught out or slip up you die in really fast. Supportive tank items also feel pretty good to buy. Zeke's give you an AoE slow which is great + boosts an allies damage. Locket gives a massive shield. Knight's Vow gives damage reduction to allies but also grants MS and sustain if your ally is doing damage. Buying tank items is just "hey I got this now".
One reason Rito is careful about buffing resistances is that they're afraid that you buy one tank item and suddenly you're unkillable, this is towards bruisers and stuff. I don't know though maaan...