Why spammy blog comments boost one's PR and rankings?

I know many people comment on others high pr blog pages with PURE tons of links with their desired anchors and their PR and rankings are getting better and better.

Since this really works, I think that explains why those high pr blogs which are open to commenting are full of links.

 

They only counts if the comments are DoFollow.
Which I don't think many good blogs allow.

 

Do you think Nofollow is really that important? I do not think the big G does.

 

I dont think your comment on blog not relevant will have more PR.

 

OK, I admit that relevant backlinks will boost your rankings, but IMO, PR has nothing, at least not much to do with relevance.

Cheers

 

the default setting of blog comment section link is "Nofollow",
there is no help for your site ranking.