Do you think search engines such as Google devalue the backlinks on Articles Sites such as Ezinearticles.com, Goarticles.com, etc. --- as it may assume its SEO people looking for backlinks?
IMO I don't think that they do so in a blanket format. There are I am sure some sites that are probably viewed as spammy and thus the whole site is devalued which would make a link on that site offer little value.
I see no evidence that google devalues backlinks "as it may assume its SEO people looking for backlinks" Some of the articles I see written on these and other sites have no or less than the allowed backlinks. Other, many of them have links to their authors home pages but they have genuine value and I have copied and pasted many of them to read further as I assume many thousands of others have also. While you and I may write articles solely for that purpose I don't think google is going to assume that is the only bases and devaluing for that reason does not appear to be happening. At least not at this point
Its sad to say... but many article and web directories are having low value to due SPAMMY site that are linking to it... Only few article and web directories nowaday have left with value...