No, but they should because Showtime Anytime dot com allows you to stream live Boxing as long as you have a provider like Xfinity, Direct TV or a bunch of others.
But to stream everything, when I am out of town I will be able to stream any show I want with the $99 Slingbox hooked up to my Xfinity set top box.
No, it has to do with broadcasting airwave rights. Basically, the same reason your local news can't simulcast the nightly news on their websites or why you can't listen to sporting events from online radio streams.