The opt-out controls are built into the web push system, which should keep the channel relatively clean. If marketers are abusing it, users will very quickly d

The opt-out controls are built into the web push system, which should keep the channel relatively clean. If marketers are abusing it, users will very quickly deny their future pushes (after the fact, Safari -> Preferences -> Notifications). If email had such a built-in opt-out feature, I doubt spam would be what it is today. Beyond that, we're definitely aware that there needs to be a steward of the channel. If people abuse it, we lose. There are things that can be done with throttling that we hope to implement soon. Hasn't been necessary to this point.