Context? This just seems to be a post from a Mercurial/Hg advocate. Mercurial could be 10% better than git, but unless it's 500% better, it will never displace it.
And when I personally engage in mercurial advocacy it with an understanding that as you say, unless it's 500% better than git – which it is not – it will never displace git. However hg is every bit as good as git and most of my advocacy (as in this mail) is merely point this fact out and dispelling quite a lot of FUD, which seems to pop up in these discussions.
My goal is to see Mercurial continue in its position as the Mac (or Linux) of dvcs' to gits Windows. That is as an honest, respectable choice that you might, or might not make for valid reasons.