Lots of folks talking about people retrying searches, or doing unneeded searches instead of typing the URL, etc. However, this already happens a lot on desktop computers (especially the later). It may be true that these things happens more often on mobile than on desktop, but this is hardly why mobile is superseding desktop.
First, I run a lot of searches on my phone because it is more practical. "Where is restaurant X?" "What time will Y event start?". Even at home, I won't go to the laptop to make this search, specially if I'm discussing something with my wife.
In the same manner, add to this to a lot of vanity searches, like when I'm discussing something with someone and I get my phone to find out some fact. "How old is the president?" "How much does an airplane weight?". I surely do a lot more of these researches on mobile, most of them I wouldn't do in a desktop, just because It wouldn't make any sense to stop conversation to search a desktop, while the phone is there, waiting for me.
Second, and probably more important, is that lots of people now have their mobile phone, or tablet, as their primary computer. My wife don't open her laptop except for writing long documents or academic work.
Like with cameras, the best computer is the one which is with you right now, and laziness to get up often beats the efficiency of my laptop even when I'm at home. Most people is using IM all the time, and the phone is with them while they're at it, and don't even consider looking for a desktop.
So, I think these two factors are adding up pretty quickly: people are using more mobile than desktop and people with mobiles tend to use search much more. If this is happening faster from expected, or not, as the article implies, it's mere statistics.