Just a stab in the dark but him (Allan) and Ryan Fleury are working on a much bigger project atm (https://dion.systems/index.html) which includes an editor too, so i'm guessing they just don't have enough time
Sure, software of the past wasn't that much better, but relative to hardware it ran on it was much more performant.
I think the main point of his view is that with current hardware advances we should be able to have a cake and eat it too. We can have both the features and the speed, but we don't care about that. The only thing that matters is to be first.
His message is very clear: Modern software is crap. It's orders of magnitude slower than it should be, it's buggy, and,yes, bloated.
And if you ever used any piece of software today I don't see how you can you not agree with it...
He is never advocating NOT using engines, but rather that one can be much better and more efficient developer with just a little bit knowledge of inner workings of an engine.
Him "spending a billion years" is nonsense. Handmade Hero is his side-side project which he does once a week for couple hours.
You can think of HH as a teaching tool (and not even a good one which he would admit himself im sure) and not 'here is definite guide on how you make an engine yourself'.
HH inspired and showed ropes to so many developers, its value is immeasurable.