if it is a fact Google is going against guest blogging does it mean we should stop writing guest blogs?
No, Matt Cutts said that it is a time out for Spam guest blogging, not for quality guest posts.
I just want to highlight that a bunch of low-quality or spam sites have latched on to “guest blogging” as their link-building strategy, and we see a lot more spammy attempts to do guest blogging. Because of that, I’d recommend skepticism (or at least caution) when someone reaches out and offers you a guest blog article.
Also Don't rely on only guest posting, try all techniques to vary anchor text and link diversity. Guest blogging is still useful, as Matt Cutts also suggested that:
There are still many good reasons to do some guest blogging (exposure, branding, increased reach, community, etc.). Those reasons existed way before Google and they’ll continue into the future. And there are absolutely some fantastic, high-quality guest bloggers out there. I changed the title of this post to make it more clear that I’m talking about guest blogging for search engine optimization (SEO) purposes.