I'd agree with you if I didn't see first-hand how propaganda starts wars.
And yes, reasonable censorship helps, e.g. YouTube blocking RT is very much positive for the whole world.
Propaganda has always been a problem and democracies and led to wars. What is different now? Also, in this particular case, what war are we stopping by banning Americans or Europeans from seeing Russian propaganda? It looks to me like that ship has sailed.
In fact, if anything, it appears to be we’ve opened the floodgates to pro-Ukrainian propaganda, as if being anti-Russian invasion means we must therefore accept all things pro-Ukraine. As with the Ghost of Kiev, people have even said even if it’s not true, we should still believe it. Since this type of propaganda has encouraged the arming of Ukraine by the west and increasing escalations, it seems like it is more likely to increase the scale, scope, and length of the war. Should we ban Ukrainian propaganda?