One of the challenges the 3E designers faced was what to do with infravision, which is a really buggy design concept. The 3E team finally decided to scrap it and create a new sense: darkvision.
An early version of darkvision for 3E worked much like a bat’s echolocation. However, I had a talk with the design team about some problems that would cause (for example, you wouldn’t be able to see fog or mist with darkvision, you wouldnt be able to read the writing in a book, and so on). Because that would do a lot of weird things to existing adventures and monsters, the designers decided to change* how darkvision worked to “just like normal sight, but in shades of gray,” which is the form of darkvision 3E players are familiar with.
So if you’ve heard the “darkvision = echolocation” line, you probably heard it from a 3E playtester (or someone who heard it from them).
* At the time, I was working on a Forgotten Realms adventure called Into the Dragon’s Lair**, which featured a long section in a civilized goblin city locked away in an always-dark demiplane for hundreds of years, this required rewriting some common details about the city, like changing the “business signs are carved deeply into the stone so they can easily be read with darkvision” stuff to “it’s a painted sign.”
** Of course, Into the Dragon’s Lair had more than its fair share of annoyances dumped on the designers, which I should talk about in another blog post. I really should get around to finishing that old “trivia and anecdotes” series of blog posts I was doing years ago with behind-the-scenes info on books I wrote…