Filters can definitely lead to censorship, which then means that someone who is being censored needs to approach a friendly miner directly (and bribe them with a hefty fee to include their transaction). Given that mining is currently highly centralised, it would mean that a shadowy world government would only need to strong arm a handful of big miners and force them to refuse business with a censored entity and thus that entity will be barred from using bitcoin. Is this not a conceivable scenario?