I don't know if you're in the industry or not, and my profession is about as far removed from the industry as you can imagine, but I nonetheless have been able to observe some film shoots in person, on location. How? Over the years there have been a couple of TV episodes and a few TV commercials shot in my house.** These were lower budget TV shows and mid to high budget TV commercials.
I can't claim I fully understand all of what they are doing with their MacBook Pros, but it seems they were reviewing footage and sometimes doing some quick editing on location, plus lots of other stuff (mixing, etc?). I can also say they may spend hours on those machines over the course of the shooting day, and there usually were no full-on hardware docking stations involved. I do recall seeing an external monitor occasionally, but more often than not there was no external monitor. They did make liberal use of external drives though.
**Where I live there is a province-wide database of shooting locations, and homeowners can submit a description and pictures of their own personal homes to that database for free. Location scouts, producers, directors, etc. can check out the database to look for locations suitable for their needs, and pay the owners directly for use of the houses/condos. The types of houses used range from run down bungalows to high end mansions and everything in-between, obviously depending upon what the shoots need. Because of this database, I get phone calls from location scouts a few times a year, and occasionally those calls result in an actual shoot at my house.
Ye were talking about different things.
Capture on location can be done in many different ways, most of the time cinema cameras will have their own SSDs with monitors that a creative director would view the capture, cuts on set don't happen footage is sent back to a studio to be edited. Especially on something like your describing above, but laptops can be used to tether and review footage, even so 15" is too small for a director to review on.
I mean come on its hard to see if you have hit critical focus on a still camera on a 15" display unless you zoom into 100% let alone for a videography.
Even so your talking about high end work, say the average youtuber... go out shoot your footage say your getting the train back as described above... ye you can import and capture footage, depending on what your using transcode, line up some footage and cut but its far more likley that they head back to a studio with a full desk set up to do the heavy lifting its just far easier.
Most plug into an external display or "Dock" therefore using the machine as best of both worlds instead of having a separate desktop. Its far easier to edit on a big screen than on a laptop even 15" wasnt that big back in the day. My first macbook pro was a 17" I still hooked that up to a 30" ACD before I bought a mac pro.
Although you say your not in the industry, you use 2 iMacs right? one to drive another in target display mode? You have a machine that does specific job... You can use a macbook pro to do everything doesn't mean its the best at every job.
Anyway back to my argument about the touch bar.
In desktop mode the Touch bar is pointless because if your attached to a screen your likely using a keyboard and mouse and the laptop will most probably be closed. Its a disjointed editing experience being able to cut like that on the macbook pro and not on any other mac computer. Having to do two separate workflows to do the same thing. Which is why its weird the iMac pro would have been a perfect time to launch a new smart keyboard... they launched the full length wireless keyboard but there was nothing fresh there. The Touch Bar has been around nearly 3 years why hasnt it been adopted anywhere else?
Anyway I dont know many people that rely on a laptop as a main machine, more of a convenience to have a high powered portable machine get work done on the road. The macbooks are powerful but they pail in comparison to a desktop for any kind of production work. Almost everyone I work with have both desktop and laptop. The agency I work for provides both, its just standard.