Blog commenting is worthless. It has zero SEO value. WordPress automatically adds the nofollow attribute to links in comments, which effectively neuters them.
Article writing also has zero SEO value if the articles are posted in blog networks (almost all have been penalized by Google), or free article repository sites (also penalized). If people repost the articles from free article sites, they rarely provide links and the duplicate content is eventually penalized. The only value article writing would have is if the articles are 100% unique and posted on your web site.
Neither of these techniques drives any real traffic these days. The increased traffic they appear to produce is mostly from spiders and bots.
"Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well-armed lamb contesting the vote." -- Benjamin Franklin