I've used CAN-SPAM many times to enforce spam marketing from businesses plenty of times.

Further, it has required unsubscribe links to be included which allow you to opt out of any further communication. That is invaluable because you can't do that now with SMS.

I'm not discounting spam filters. They have certainly made life easier, but for things that _aren't_ caught by spam, I have at least some recourse by unsubscribing.