modern inventions are orders of magnitude more complex than anything in the past

Well, in a way that's always the case with inventions. I think when the first modern submarine (it's just an example) was built it also was a marvel of alloy purity and manufacturing precision compared to anything in the past. It's just that in the last century we observed a lot of technological progress because we started doing research in a lot more directions and in much higher volume. We caught up to our technological and theoretical knowledge and now the progress will slow down. Only to explode again after another breakthrough, as we often move in sinusoids, but that will be in one field + how it can help other fields, not a bunch of fields developing all at once in a short timeframe