I don' use black hat seo technique ever and its not good for those who using this technique. Today google is very strict and if we will do spamming on our site then google may be penalize our site.
This is totally wrong said and seo will never end and without seo its veryhardto get our keyword top on ranking and stay there on top for long time. We can't say that seo will end but we can say that seo is totally change now and now we should need to do work quality and authority work.
Blog commenting is very good way to get back link for site and also to get refferal traffic for a site. But you should use blog commenting on relevant, high pr and do follow link sites to get better result from blog comments. Blog comment is also very good source to get knowledge.
use woo rank and it really a good website and free of cost.