The internet and cable television are different forms of broadcasting.

Google IO brushed on this topic and quantised the marketing potential of different forms of broadcasting in a graph:

http://i.imgur.com/akG0F.png

TV advertisers are restricted to one way flow of information, so advertising is about building brand. It's difficult to convert this into conversions. On-line advertising however have accurate statistics because of the available analytical software. Advertisers stick to conversions only as it's still a wild west when it comes to accurate impressions (even Facebook has been caught cheating on viewer counts). Until advertisers cater to surfers the full potential of on-line advertising won't be realised.

I assume it's what caused the shortfall in Google IO's graph, I personally feel on-line marketing understated as a medium.

And facebook is not the internet or television, which is why it doesn't make any sense as an analogy. Comparing how many TV viewers MTV gets to how many internet users facebook gets would be a reasonable analogy. Comparing how many internet users facebook gets to how many people have cable is nonsensical.

In my opinion, if you are sitting on a marketing budget for a retail product trying to make decisions, they are important facts to have.

I would say that knowing the absolute reach of as many channels as possible is important including billboards etc. If you expect a 0.5% conversion rate, as long as you filter out ones that reach less than a million people a week, all of your options represent a serious return.

I have no idea what you are trying to say. You think that making a bad analogy is an important fact?

Facebook and cable have the same customers. That is why it is a good idea to talk about their respective reach.

That doesn't make a senseless analogy any less senseless. I didn't say "you shouldn't talk about how many users facebook has", in fact I talked about how many they have. I said that the analogy he made doesn't make any sense. Facebook isn't comparable to cable, it is comparable to a channel.