Ohmwrecker is still suffering the same fault it always had. Those who do want to build it never are afforded the chance to.
Diving junglers? Boots and Jungler item come first, and by then buying a good armor item will pretty much let you tower dive anyway and be more effective overall.
Tank supports? Maybe - if you can scrounge up the gold for it as an earlier buy. Otherwise you either buy an armor item to dive anyway or need a defensive item to live through a losing lane. If you do get ahead to be able to afford it, buying a better armor will let you do what Ohmwrecker does and more.
The stats on the item are ok, which lends itself to being a lower priority buy. Given that one only initiates a turret dive with an advantage, Ohmwrecker becomes redundant. If you do buy Ohmwrecker, you're trading extra health/armor on the item itself to make up for having less armor/health to dive a turret. Doesn't make ANY sense.