I am pretty sure google will never make it so blog comments weight nothing as this is esencial for blogin and link building. Tomorrow you will come up with the idea to devaluate links from articles because there is too many of them out there or link from social bookmarking as its just a bookmark and has no value into it ? Makes no sense right ? Right. What about directory submissions maybe devaluate them too. In one thing I am certain, most of the people who write this crap here have no idea of what it really is and how it really work. As far as it goes the best thing you can do is just build back links from many websites where you can and as much as you can, including multiple back links from the same ip/website. You can always go for related websites as it can get you some targeted traffic in the process sometimes. The only things we are all certain and google has stated is that you need to build links, content and if you ever SELL links which is allowed, to rel="noffolow" them. Another topic I see people speculate a lot instead of simply searching through google's webmasters forums.
And as I mentioned early maybe if you keep a track of google's webmaster forums you will know by now that they have been knowing for a while now if the links are coming from comments. Instead of trowing some empty presumptions .
The best linking strategy is to combine all of the methods; directory subs, article subs, authority linking, 3 way, reciprocal, blog commenting, forums, etc. and do it as randomly as you possibly can. You want a natural link profile!!!
I am not sure you got your facts right. Why does google give importance to 'links'? Because they think sites will link to each other naturally and the best sites will have more links. They will also have more links from sites that have more links. Now 'naturally' people will link to their favorite sites in their niche. Or they will link to popular 'generic' websites like cnn or google. A link to diet pills site on a cricket score site stands out and will not get much link juice. Apart from that surrounding text has a lot of importance in link juice and this effect will be lost if links are from a completely different niche.
A relevant backlink with keywords matching the landing pages are the most beneficial. Trying to tell people otherwise is just displaying a lack of knowledge on the subject TBH.
1. Google only Counts the first 100 links on a webpage: A few years ago people noticed that only about 100 links on a webpage where being counted by Google. So they thought that Google didn't like webpages that had over 100 links on a webpage. This was true but the reason for this was that Google stopped caching the page after a certain amount of kilobytes. So any links that were after the cut of point were not being counted, Google has now increased the size of the cache due to larger WebPages in modern websites. I would say that 100 links in any webpage is too many just for a usability standpoint. 2. Links from other websites can harm yours: This is another myth if this was the case if would be easy for your competitors to add a link to spammy websites to make your website suffer. Only websites that you are linking to can harm you, more on that in a moment. 3. Having External links in your website are bad: People used to think that it was bad to have too many external links on a webpage as this will dilute your strength as its better to have incoming links and not external links. This can be true if you are linking to bad website neighbourhoods. However Google has stated that if you are linking to authority websites that are related to the content to your website and will add visitor value then this can be good. As this shows that you know what you are talking about. 4. Links form high Pagerank websites are best: This is a myth this is only really beneficial to website that are already have a high PageRank. It is uncommon to find a high PageRank website linking to a PageRank 2 it just looks unnatural. If you are looking for links you should not be concerned about PageRank you should look for WebPages that are relevant to your content and that the visitors will find valuable. 5. Links from .edu websites have greater strength: The reason this was thought to be true was that traditionally .edu and .gov website are strong websites anyway and are an authority within there industry. So receiving a link from here carries more weight. As Matt Cutts said a link is a link. Every link is treated the same, however a link will then be put through a filter and may be devaluated depending on many factors.
This generalization is a myth and certainly not true. It is more likely to be true if you substitute the words 'non related pages' for 'non related sites' but even then there are very many exceptions. - Michael