While there are some key concepts to things like databases, the fact remains that your 1985 database would not be considered sufficient in todays world: It would have too many limitations, lack features we now take for granted, would not scale to modern data requirements, etc. Supporting all that "modern" functionality is non-trivial and requires a huge amount of effort. You can't just say "Well, we figured out space and computationally-efficient hashing, so relational databases are well on their way to being feature-complete"

There's a reason we haven't stuck with 1.0 on our platforms, and it's not just security or a desire for a bigger version number: New demands required new functionality and new ways of building things.

A great example of this is the evolution of FB/Google/Amazon. Portions of their core tech have been completely re-written over the years for marginal gain, but there is a large premium to being the best in tech.

In other parts of the industry every new cycle enables some new area of tech, and those marginal gains become the minimum bar for entry. e.g. Deep Learning and Computer Vision, distributed systems and cloud computing/SaaS.

- No process or kernel security (processes could rewrite kernel code)

- Processes could effectively disable the scheduler

- Supported only a single, fixed address space: both a massive limitation and a performance hack that made the system bearable to use

- Single-user

- No security model

There are embedded applications these days where not having these features are deak-breakers. Let me assure you: if you re-implemented the original Amiga OS feature set it too will be screaming fast. The tricky part is keeping it fast once you start adding protection and additional functionality on top of it.

And largely what happened when you tried to implement more complicated applications on top of these primitive systems is that they would crash the entire system, constantly.

Today I'm working on systems with memory latencies from l0 cache all the way to tape storage. And it's getting worse.

Edit:typo