I don't think that holds true quite as much today as it did back when Voltaire said it. He was calling out authoritarian structures like the christian church if I remember correctly. While certainly still true in totalitarian systems like dictatorships, it's a somewhat different situation in democracies for example. In a democracy you are generally allowed to criticize anyone. However, powerful entities like big corporations and the very rich might still abuse the system to sue you into oblivion.

Also this quote gets misused quite often by people who do not understand the difference between hate speech and criticism and by people who think being called out and criticized for their words is the same as being "not allowed to criticized" or silenced.