Another aspect was that the systems themselves were simple enough to fit in your head completely. Limited hardware, maybe a few special memory addresses or int

Another aspect was that the systems themselves were simple enough to fit in your head completely. Limited hardware, maybe a few special memory addresses or interrupts, and that was it. If you could read from a keyboard, write to the screen, and load and save files, you could already do everything that almost any commercial software could do. Going from that to more modern systems (even Windows 95) was a giant change. So many libraries, frameworks, and systems to know about. And you need to know them and work with them in order to create anything remotely like a commercial program. Your programs don't have full control of the entire system. So yeah, there's a lot more stuff available now, lots of free languages and tools, etc. But it's also a whole lot harder to get into.