I spend all day writing C++ or Python, and like playing around with Turbo Pascal on a circa-1984 Kaypro 2 as a hobby machine - the projects are certainly smaller, but my edit-compile-run loop on my Kaypro is usually faster in practice (even running on a 4 MHz Z80 with 64KB of RAM compared to an 8-core 3+ GHz workstation with 64GB of RAM) than my 'modern' work. It's genuinely crazy to me how usable a 40 year old machine is for development work.

TP was just so awesome, it was like a superpower compared to others waiting 10-20x as long for each build.

For me the big thing was all the latencies stacked together. Slow hard drives, slow floppies, god help you if you swapped, etc. The era was mostly waiting around for the beige machine to finally do its thing.

Also, much like some people are Excel wizards, some people were Apple II monitor/mini-assembler wizards or MS-DOS DEBUG wizards, or whatever other thing already lived natively on the machine. If someone has strong knowledge of the machine, a handful of carefully targeted little software augmentations, and well-developed muscle memory for the commands, watching them use a debugger/monitor can be almost like watching someone use a REPL.