you think that guest blogging on someone's site, that they have given permission for you to do because you have quality content to aid their reader's
There's a huge difference to the sites I own and operate compared to the junk blogs that frequent the web and the trash of society who abuse whatever limited invited registration rights that are given. The trash being freelance SEO's that openly spam others work/property. So nothing distasteful in that right?......

some dodgy, invented lover lover, unregulated, guru-wannabee service that reigns terror in wasted hours of delete time for publishers is fine I suppose.
because your content holds substance.
What you are talking about and confusing with are the pure, info portals and vortals like: TechCrunch - as majority of blogs are made for adsense trash, and not applicable to what a true info site should be and those trash sites must attract spam links down to the ease of entry.
Also the ratio between the thanks votes and OWG's amount of posts only clarifies that he (and others) will get a certain amount of thanks in relation to the amount of posts made - so nothing impressive in those stats from what I can see. Now I've never used his services, so cant comment on results, then again anyone who relies on forum posts as a quality guide of results, is asking for trouble.
We usually give a wide berth to such companies, as we look for other factors of substance eg: like a real bone fide product before we even consider using anyone. We see forums as a dumping ground for FFA type link spammers, its just some spammers are now more inventive than say 10 years ago, and for spam to be effective, its got to look legit, and the 'I'm your friendly forum neighbour' is better for sucking in the suckers as more likely to be accepted than a direct link spam drop. But there are tell tale signs on how to tell the real helpers of the web, from the snake oil sellers.
My point? if all these link spammers, forum advisors, PPC guys etc are so great at making others rich, then why don't they build a site and make themselves rich instead, it would save them a heap of marketing time/effort. In other words:
If I knew a way to make you a ton of money, would I tell the world for £100 a time, or keep it to myself and just get rich.... you can get this secret answer from me, just send me a cheque for £20 to this address first though ok, and I promise to send you an ebook with the secrets - honest! But please ensure its sent via Western Union ok - most important!
Now, the above seems to run the same risk as doing business with a complete stranger on some forum right...
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Now I'll tell you that getting backlinks has nothing to do with secret relationships, but everything to do with 'list ownership' - these are lists of various quality that SEO's use to link build you a presense (cough, sorry link spam you about). Its bad news and causes huge problems for the unsuspecting client, and makes the SEO spammer their cash.
I feel from reading posts on here/SEO threads, that many assume acquiring links is a sort of art form, but its not as access to free weblinks is heavily controlled by the publishing sites with no easy route into the sites. So that leaves us with 'open forms' which will be the naff, crap and totally unrelated junk of the web eg: the blog owners who couldn't give a monkeys behind as long as displaying bs/nonsense comments makes them feel like a king of the web amongst their like-minded adsense peers.
I think you'll find that SEO will drain your pocket faster than you'll make it back.