Monday we covered how John Mueller of Google said that going mobile only is fine, in that Google will index the mobile only site and rank it just fine both on mobile and even on desktop. Just because there is a mobile-friendly algorithm that promotes mobile friendly sites in the mobile results, it doesn't mean that Google will demote non-desktop friendly web sites on desktop results.
That was the point of why I covered it. I did not cover it to say that Google wants you to only build mobile only web sites, but that if you did, it should not hurt you in the desktop results.
John Mueller at Google felt the need to clarify his comments and posted a message on Google+. He basically said, just because Google will rank mobile only sites fine in desktop, it doesn't mean it is the best practice for your users. He said you need to think about all your users and maybe going with a responsive design is your best bet there?
Here is his post:
With regards to (paraphrased) "a mobile-only site is fine" (a comment for one of the questions in a recent hangout), I'd just like to clarify that just because you can do something, doesn't mean you should, nor that it's a best practice :-). If all we have from a business is a mobile-friendly site, then we'd rather index that than nothing. That obviously doesn't make it a great practice though. A good way to make it work in both worlds would be to have a site that uses responsive web-design techniques to adjust to the size of the user's device / settings.
I can imagine some sites starting off with only a mobile-friendly website (it's kinda like businesses that use a mobile app instead of a website), but I'm sure most would do well to also provide an awesome experience for users with larger screens (be it a desktop, laptop, mobile, TV, etc.).
I doubt any of you need this clarification here but if you did, here it is.
The cool thing is that, again, Google doesn't demote mobile only sites in their desktop results.
Forum discussion at Google+.