It looks like these things are all over the board, going from useless and detrimental, to actually good, most of them contextual.
It's like rfkj got brain damage and then tried to make sense if it. It's like he almost gets it but then veers off to the side.
I was actually just talking to a person about this. How it's pretty easy to pursue truth of a topic and continue down the wrong road, all just from a wrong premise or even a missing fact that gives you the wrong perspective and direction. Continuing to deepen an "understanding" of something, stubbornly. Add cognitive biases to a deep impairment, and now you're ready to run the United States apparently.
Yeah but then I can't tell what filetypes they are. Having the type directly in the name is an awesome convention. And theoretically, it prevents the os from having to read every file's contents. And it's good for not having to use thumbnails. So you can have more condensed file browsing. It's also better for proprietary filetypes and new things since the os doesn't need to know wtf something is.
Your logic reminds me of using nondescript variable names in programming. Yes, the system will probably know, but I'm the user, I'm the person this is all for. And it's good convention to have good naming convention. File extensions are nice to have and good convention.