Ugh. MS-DOS 2.0-5.0 inclusive didn't have a defrag tool. It was introduced with dos 6. While it could be helpful, the fact that we went more than a decade without a defrag tool as part of DOS reinforces just how optional it was/is. The benefit of defragging was that it would be marginally faster to read a file that was stored contiguously instead of in pieces. There was the side benefit as well that it was easier to recover data that wasn't fragmented.
I'm not aware of any legitimate 'Problems' caused by simple fragmentation itself. That tech guy was not just wrong in his behaviour, but also in his technical knowledge. What an ass.

Your background of being the family computer expert closely mirrors mine. However, I was too stubborn to ever call support, and instead stumbled through slow internet searches and manuals. Wild how much easier computers are to operate these days.

Sorry for your bad support experience though. At least that hasn't changed!

Absorb my twin I will.

Obligatory "I can hear this GIF"

The looping made me look for "Contents modified - Restarting..." 😅

Hard drives used to be irony, now SSDs are more Silicony.

…

I’ll see myself out.

Fun fact is the turbo button wasn't actually turbo anything. It pressed in was the default and designed speed. When it was depressed it set it to run at a lower clock speed. This was meant for older games where aspects of the game like movement and attack speed were tied to the clock rate. With a high speed cpu the game was unplayable so you take off turbo mode and it mostly fixed the issues.

I felt like the difference was only obvious if the disk had gotten really bad in the first place, but maybe it was just psychological from seeing the colors move around.

Oh I just recently replayed Myst. Only outshined by Riven, such a great game.

I'm guessing dummy.bin is a zerofile?

Is Gen Z: a network drive?

This is the defrag I remember most. Back on a 286/386 it would really make a noticable difference in how fast files and programs would be found and loaded. From my Pentium-based Windows 95 machines and onwards I never noticed quite the same impact of defragging my drives.

no

https://datarecovery.com/rd/why-you-dont-need-to-defrag-hard-drives-anymore/

It has nothing to do with the type of media and everything to do with the file system being used by Windows, FAT.

I hopelessly did this on Win 98 without a clue what was happening, so why not?