Ok so lets talk Steel-Type Bulky boosters. Here are the better ones:
Jirachi
Bisharp
Curse Ferrothorn
So, again, use Scizor for what he is best at, NOT for what other pokemon can do better.
Jirachis CM Sets are hard to use with all those excadrills and Landlos running amok and it is also a special attacker wich makes scizor and jirachi hard to compare to begin with.
Bisharp is hardly viable in OU and isn't bulky.
Curse Ferrothorn is OK but can't hurt other Ferrothorns not too mention that it doesn't gets priority so everything faster with HP Fire will fuck you up.
Scizors SD is is extremely viable he got a shit load of resistances, Priority to negate its slow speed, reliable recovery and can set up on Ferrothorn without worring (he may get paralysed but he is slow from the start and Bulletpunch bypasses speed anyway) and thats big because this things is extremely common.
Saying that somethings not viable, because something else can maybe do it better is stupid. Sure maybe Ferrothorn is the best spiker in the current metagame but that doesn't means Forretress, Skamory and Deo-S aren't viable because they all serve different niches.
Scizors niche is his fantastic typing that helps him to get set-up opportunitys , a Powerful Priority move and a high attack stat to begin with.