It sounds like you're advocating for pushing censorship responsibility to the user. I agree this would be nice — in fact you could consider uBlock Origin a form of client-side censorship that already exists. In practice, I'm not sure how much adoption such a system would get, if used for censorship purposes. The main problem is the underlying truth that most censorship proponents are not actually pro-censorship of the information _they_ consume — they're pro-censorship of the information _other_ people consume.
Even if you _could_ find a user who wants their client to hide information from them, that user probably doesn't want to filter their own spam, too. By default, the client already expects the server to fulfill a gatekeeping role in filtering (censoring!) spam. In fact, this is how we got here in the first place – we delegated filtering mechanisms to service providers, and now they're simply expanding the filter.
Personally, I'm in favor of a simple but likely effective regulation: Any service that renders a feed of third-party content to the user must default to sorting the feed in reverse chronological order, and must reset all current users to this default on the day the legislation goes into effect. Of course, this only mitigates the feed-based, mostly social-media problem — it doesn't solve the issues with search results (or auto-complete suggestions, for that matter). For search results, a client-based model wouldn't scale, as client preferences need to be evaluated at time of indexing, not when returning results.