That audience is some huge percentage of the internet userbase, because some huge percentage of people are "clueless and naive." So people who want to just make money off a widely read website would do well to do what works. Just like how in the mobile gaming space irritating pay-to-play/in-app-purchase driven "games" are the money makers, and people who make games in order to make a lot of money should probably make a game like that.
Well, everyone has to make their own ethical choices.
Personally, I don't need the karma of annoying the customers, regardless of how much it may seem to work in the short term. I mean, you might as well be Zynga if you're going to do that.
No company survives in the long term by annoying and/or abusing their customers.
This is simply not true. Sure, you'll get signups from people aren't actually in your target market (clueless and naive), but at the margin you'll also get signups from people are intelligent and high value prospects that wouldn't have otherwise signed up if you weren't aggressive about offering it.
To deny the potential value of x by categorically defining all the people who you think would respond to x is ignorance at best and most likely just hubris.
You'll lose the people who click the back button the second one of those gets in their face and never return.
Hubris? Sure, if you want to call it that.
Personally, I think that expecting a person to sign up for your site based on no evidence whatsoever is pretty damned hubristic. The message I get is "WE ARE SOOOOO FULL OF TEH AWESUM THAT YOU WILL WANT TO GET SPAMMED BY US DAY AND NIGHT!"
Yeah, good luck with that.
Note that I wouldn't mind nearly as much if the site was clever enough to noticed that I'd looked at 15-20 pages (or whatever) and THEN asked me if I wanted to sign up. But it's never that way. It's always right on the front page, before you can even SEE what's on the site.
There's not a chance in hell that I'll sign up for something like that.