In all of the discussions on HN about vi/m this is probably the most intelligent question I've received after posting my opinion.
I've been coding for 16 hours straight and have at least another four in front of me (have to deliver tomorrow AM) so I don't have a ton of time to answer this.
I'll use today as my example of how irrelevant (and counterproductive) vi/m can be.
I'm working on a large Django project and cranking out apps like there's no tomorrow. I use PyCharm for this.
Here's a case where experts are making it their business to deliver a superior tool that allows me to get my work done. It has myriad tools configured and configurable to help me. I don't have to futz around with weird custom stuff. It is intelligent about Python, Django, JS, jQuery, databases, HTML, packages, Git, Python console, Django console, etc. It can even talk to my servers. PyCharm is, in my opinion, a nearly unmatched productivity tool.
I lied. I am working on two large Django projects simultaneously because some of the work for the new project entails porting from an old one. So, two PyCharm windows on two 24 inch monitors and two browser instances side-by-side on the third monitor.
Can you setup vim to do some/all of the above. To some extent, yes. I haven't used it at this level in quite some time so I can't answer the question. What's the question? Can you setup vim to match PyCharm feature for feature? I don't think you can, and, if you could, it'd be a nightmare.
A lot of the vim "religion" centers around keeping your hands on the keyboard, not using the mouse, carpal tunnel and speed.
Keeping your hands on the keyboard is irrelevant unless you are a data entry clerk. If you are a software developer you are far more likely to spend more time doing things other than typing. Designing data structures, diagramming databases, researching approaches to solving a problem. Thinking.
The above is also used hand-in-hand with "vim is faster". Yeah, again, if you are a data entry clerk entering tax return records this might have some value. Software development? Nah. The time one could save by only having to move a finger a few centimeters is but a rounding error in the context of any non-trivial software development project. It's silly, really. Take the entirety of a project and multiply typing time by, I don't know, 1.25. It would still be insignificant when compared to the overall project time. Debugging alone takes orders of magnitude more time than anyone could save by typing faster.
Not using the mouse. You know, those of us who grew up using, designing, building and programming computers that did not have a mouse were ecstatic when the mouse arrived. It's just plain silly to malign the mouse. I will say that I switched to a thumb operated trackball a long time ago. I don't go looking for a mouse. My trackball is always there, quite literally touching the right edge of the keyboard. And I don't have to move it all over the place to use it.
Carpal tunnel. Serious problem. I suffered from this about fifteen years ago. Doing 18 hour days in front of the keyboard was red-hot painful. I tried different ideas. I knew people who had to have surgery on both wrists and were never again the same. I wanted to avoid that scenario.
I ultimately did two things: First, I switched to a thumb operated trackball. Mice are not designed right and you have to move all over the place all the time. This is very repetitive and not good. Second, I designed and built my own desk. I welded a steel framework that supported a surface for the monitors at 29 inches off the floor. The framework also had a full length shelf in the front with the surface dropped down about three inches. The front of that shelf had a 2 inch raised lip. So, my forearms rested on this lip and my keyboard and trackball were two inches below that. My hands naturally drooped into that cavity. No more carpal tunnel. Being in front of the computer doing everything from mechanical to electrical to software engineering using various interfaces for 16+ hours is normal for me. I have not had any issues in 15 years or so. None.
All of the arguments for vim are simply irrelevant. The only argument I could find for knowing how to use it at a basic to mid level is this: If you find yourself having to access a remote system with a computer that dates back to the stone age you might have no choice but to have to edit files remotely and you know that vim/vi will be on that system. Personally, I have never in over thirty years had that problem. These days I'll use something like CuteFTP if I have to or, as I said above, PyCharm and other IDE's (PHPStorm, etc.) know how to talk to servers and allow remote editing "in comfort". I mean, you can buy a $200 PC laptop with a large 17 inch screen, full keyboard, etc. these days. No more excuses.
Bottom line: vi/vim don't make sense because they do not provide any advantages when compared to state of the art IDE's.
Wow, I ended up typing more than I wanted to. Oh well.