I don't know how to feel about this.
Any production app should already use a reverse-proxy (e.g. NGinx or Varnish), and blocking and similar logic can already be done there. I think that the problem does not warrant its own solution at this level.
So, it's hard (or can't) detect in the proxy layer or with something like Cloudflare. That's why we need a something like Sikka, which understand DDP, the protocol behind Meteor.
Anyway, only we detect bad IPs. It's a good idea to ban them from the network layer.