The problem is that if you're somewhat high profile, and guest post on other higher profile sites you should be okay. Move down the "food chain", and Google doesn't look so kindly at your guest blogging strategy.
There are other benefits than SEO when thinking about guest blogging. Personally I see guest blogging as awareness building first, with any bump in SEO a nice bonus.
From your linked post, it seems there's just not much SEO value to gain from guest blogging, but it also doesn't hurt (unless you're obviously spamming).
Groove's post is all about the traffic and trial sign ups they received from guest blogging, not about the SEO value.