...this provides an exceptionally high opportunity for inequality

Yes, scalability of software is one thing. Another relevant thing is the so-called flattening of the world: it is becoming more connected and less diverse. The barriers to flows of people, goods, information, money are being flattened into nonexistence. This leads to winner-takes-all situations: if your product is better than everything else in, say, Germany, it's likely that it is also better that everything else in the rest of the world.

Some simplistic macroeconomic simulations have suggested...

Color me sceptical. I think the key word is "simplistic" -- unless you show relevance to the real world it's just not useful in any way. Might even be harmful on the general "mind contamination" principles.

...until the 90s. Then the poor actually get worse off again.

That's debatable. Off the top of my head (I stand ready to be corrected on facts), the median salary of the lowest quintile stagnated or even fell a little, but the median income including benefits continued to rise. Also the decline is pretty much limited to men without college education. If you're a woman, or have a college degree your income even without benefits continued to rise.