You've missed the point that it does more because it allows resistance while a silence offers none. IF you are silenced all you can do is run.
If someone is Fazed, they can Zhonyas, flash, ghost, heal, use CC breaking items and with these effectively get away from a situation that would of killed them.
Ah! I see that now. Was not clear from reading the OP.
hmm...
I see where you're going with it, and basically it forces players to use their SS and items. Silence already lets people use Clense and QSS, but the ability to, say Locket shield yourself or BotRK active, might be an intersting angle of counter-play while you anxiously walk away from, Talon for example.
The Blind/Silence/Slow aspect is extremely OP even though you can still Flash/Ghost/Heal/Barrier/'Item Active'. This would basically be the best of both worlds with the only counter play being a newbie not knowing to take flash into lane against you and to save it for just this case. In fact, that is the only counter-play to this new ability: Flash.
I've decided I don't like it because it combines Blind, Silence and Slow into one ability while giving back almost nothing. The only two meaningful things that you are offering to the victims are
and
which is hardly a fair trade.