honest question, why do you care how they evaluate 'porn' websites? as long as we're still capable of switching between 1.1.1.1 and 8.8.8.8, what's wrong with providing this additional service? it really doesn't have to be a joke...
Because it is very likely that governments (such as the UK) will attempt to force all traffic to the censored one by law.
Because it tells governments it is possible to do. Years later we may start seeing devices with DNS servers hard-codded to this. And also because blocking like this is not very effective. You can't block every "harmful" website on the internet, plus there are various proxies. And what is "harmful" anyway, who decides? This also brings questions - are there already blocking something on 1.1.1.1 or will they propagate some blocks from 1.1.1.3 back to their main server? Any blocking is very wrong and may cause freedom reduction in the future.