What is a white-hat link these days?

These days you can't:
  • use blog comments
  • use articles
  • use press releases
  • use guest posting
  • use web 2.0 blogs (apparently mentioned at SMX Advanced)
  • use paid reviews/mentions (nofollow "forced" by Google)

We can always use these methods in building white hat links as long as one is not spammy or resorting to black hat methods.
 
All the techniques you've mentioned are actually still good enough for getting links.

Blog comments can bring additional traffic to your site and help you add credits to your reputation in the niche. And if you really contribute to a blog with your comments, it means that you can ask a blog owner for a guest post, and the latter is a very powerful and absolutely legit seo technique.

As for articles, if you create a unique copy full of interesting and helpful information and place contextual links in it, then it's nothing wrong with this method. On the opposite, content marketing and proper distribution of your content online are now worth focusing on.
 
All of them are effective ways of getting you links and I partially agree with you since I read an article recently that these approaches are considered black hat. I'm really confused on why it is so. However, the only sure answer I know is you can get organic backlinks through writing valuable content and having people link to you.
 
This is something I've never really gotten - I find that most quality sites DO indeed have a large number of outbound links, linking to other relevant resources, more information, related blogs, and so on. News sites often do this, wikipedia has the entire bottom stacked with outbound links, and if you go to a decent university you're told to look for sites that can verify their sources (often with outbound links).

So... what gives?

If you look at the true original PageRank algorithm it's just a fact that still holds today, but today PageRank is such a small part of the equation that it's a non-issue. If you're talking spam, you want to spend less effort on a page with 500 other viagra links but there's no place for it in white hat. Even way back, we "white hats" only considered it much for link trading which was at the very least gray hat.
 
You have to do quality work according to google guide lines. You never do that spamming for your site. So you do guest blogging, social media profiles, newsworthy press release & local profile links.
 
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