I think the better way to put it is that silence needs to come at a high cost.
Cho/garen's silence is short range with the latter being right in your face. These champs also have strong ults that are about the same range with very little they can do outside of it.
Fiddle/ malz silence is used to bully and set up. The damage that they do is minimum, but with it they can land a more powerful move uninterrupted.
Silence isn't the worst cc, but it should also be noted that all the champs that had silenced removed had a few things in common. things that the current champs with silence don't have. Mobility.
Leblonc, Kass and Talon had high mobility in addition to their silence which allowed them to burst down opponents with no opposition or punishment. If they land their silence they could burst you and jump out with no risk to their health.
All the champs that have silence in their kit currently risk something when they try to exploit the weakness their silence brings. Garen/cho has to be in melee range. Fiddle is squishy and outside of his fear and silence can be quickly bursted down so for him to act on his silence is risky. Malz silence is the safest of the bunch, but can be dodged as it is a skillshot. Even jax (Which I might add does not have a silencet he has a dodge) is very short range with his stun and it has a long cooldown. If he uses his jump and stun and the fight goes south he has nothing to really save him.
My point is that riot doesn't want silence (or any kind of damage immunity ability) to be unconquerable. If they have an ability of this nature, they have to trade either their engage or escape; both of which are vital for assassins.