This applies to more than just programming, like spreadsheet work as well. A user who's learned End-navigation or fill-down shortcuts can get a complex Excel sheet done in significantly less time.
Novice speed does hamper efficiency. Finding alphabets, numbers and symbols on keyboard interrupts programmers' thought.
Fast does help much as programmers do not type much one at time but thinks more between lines of code. Usually programmers write a few lines even a few characters for adjustment.
For programmers, good use of editor is more important. Able to use keyword short-cuts to cut and paste, replacing pattern of text, finding text, moving text between files is a key to efficiency.
I watch "over the shoulder" of many software engineers at my (Windows-based) work, and 90% of them work at a CMD shell/console with QuickEdit mode disabled; software that I'm responsible for spits fully qualified logfile names out to said console, but rather than copy + paste the filename into Outlook's attachment File Open dialog, they laboriously click their way thru the "Explorer" dialog pane trying to find the same file. I sometimes point out that they could easily copy and paste the name from the console into the dialog, and some of them have an "aha!" moment, but most simply don't "get" it.
OTOH I've watched experienced unix developers who type at fantastic speeds, but with a significant error rate: bzzzzz (a command line) enter [error]; bzzzzzz (a whole new command line intending to duplicate the intent of the first) enter [error]; (third time's the charm?). Slow down or use line-editing? No... These are far less the rule than the mouse-click-happy Windows users, but clearly there are many ways to be inefficient...
The fewer times I (a marginal typist) am forced to type out a copy of text I see on the screen, the more productive I am. My work processes are optimized along this axis: let the computer do the work instead of my fingers whenever possible.
Sure the benefit of typing 80 wpm instead of 60 is not that much. But the cost isn't much either, it happens naturally for heavy computer users.
If you're not typing reasonably fast, one has to wonder: why not?
No doubt a few people will have some good reason why not, or just say "I'm new to computers". But others will have a dumb reason. Others won't have ever thought about it. So you can learn about people by asking this.
It's kind of like: any serious programmer should learn a decent text editor. Yes you can code in a crappy one. Yes most of the time is spent thinking not text editing. But if you aren't using good tools one has to wonder: why not?