If you follow someone on Twitter, that means you want to get their updates. And it's trivially easy to mute people on Twitter/FB so that you can stop seeing people's messages without risking offending them or hurting their feelings.

Another reply mentions having people who don't want to read your email newsletter set up filters to get rid of them. This is possible, but more work than a two-click mute on social media platforms.

Don't get me wrong — I'm not saying FB/Twitter are "better" — just that this solution occupies a middle ground that creates different privacy/relationship issues.