There are laptops for much less that would work easily well enough for mobile recording. There are also laptops for less that would do well enough for people with more modest production needs. But if you're talking "desktop replacement" feel (like my laptop has a desktop CPU, room for four harddisks and three video outputs) then I think that's about where you're at.

Starise
Many of the videos Cake has put out use laptops as demo units. When they go to NAMM or similar they seem to be using lappys. Maybe they see a trend away from  desktops?
 

Keep in mind that it's a whole lot easier to carry a laptop on plane... and to/from a trade-show.  
 
If you're used to the performance of a well-configured i7-6850k (or better), you won't find that in any laptop.
Our clients who compose for TV, Film, Video Games (pushing performance limits)... are all running fast desktops.
 

Another reason for running desktops is the price .
The cost for a compareable lappys are  higher ,that said
the sales of (decent )desktops are getting lesser in market share-
could be that laptops are getting cheaper as desktops cause of that in a while.
 
regards

If you only need one system, yeah. If you need a laptop anyway, it might be cheaper to invest in a really good one and forego the desktop altogether.

Of course Jim is right, you can't put something like an 6850K in one. For absolute top notch performance, desktops are still king and I think they always will be, simply because of heat dispersion and component size. But any modern quad core i7 can run any DAW comfortably for all but the most cutting edge needs. An i7 6700 (non K) is plenty of power for me for some time to come and that works great in my laptop.

Laptops are all about convenience, rather than cost effectiveness.  If you need that, great!  But they are mostly disposable items.  Like a smart phone.
 
The absolute best way to a decent cost/performance ratio is to build your own computer.  That way you buy exactly what you need, nothing more, nothing less.  Old parts can often be re-utilized, such as cases, drives, and power supplies.
 
Think about it, every time you upgrade to a new laptop you decommission the old case, power supply, keyboard, and monitor.

That's true, and you pay for it. At the same time, desktops aren't as "upgradeable" as they might seem, with Intel changing sockets and chipsets so often. And I've been migrating hard disks and interfaces between laptops for years. But there are definitely trade-offs.

Yup, I think that Intel just changes the sockets to force more motherboard replacements. 
 
I understand that there are generational changes that will make this necessary, such as adding support for newer faster memory, I/O ports, and buses.
 
I pretty much accept that a desktop upgrade will require at least these two items:  CPU & motherboard.  And sometimes RAM, for example if moving from a DDR3 to a DDR4 based board.
 
But often bundle pricing deals can be found for these three items, and all you have to do is swap them in, and everything else can usually stay put.  With Windows 10, you can even do this without re-installing the OS! 

While I can appreciate all views on this subject, there's  one other option for the portable user that can potentially replace a laptop in a live recording situation. -Portable recorders-
If all an engineer is doing is capturing remote audio for future editing, simply use a decent portable recorder and later dump the tracks to the studio computer. You can buy these for much less than a laptop.
My old Zoom has two mic inputs with phantom power and two on board mics.

Though not an inexpensive audio interface, the Fireface UFX supports direct recording to its USB port.
Perfect for capturing remote multi-track audio...

Fair points, but going back to the original post the question wasn't so much what affordable options for on-site recording are but whether laptops in general can replace a desktop as primary DAW. Answer: mostly yes, with some caveats.