The lists a relay applies has implications for its users — this might be a service, but is more likely to be a hindrance, because it's easier to apply more filters, but not so easy to un-filter results. Using lists makes sense, but applying mute lists is probably not a good idea, since you can mute something for multiple different reasons, which is why I mention NIP 32, it gives you the granularity you need to make a more educated filtering decision.