In 1995 getting 128MB of RAM would have been quite expensive. In 1999 not so much. One of the easy things to do with NT or 98 in the 98-2000 era was to put 128MB of ram in when it suddenly became very affordable. It was a night and day experience. I had one game that ran absolutely rubbish in 1995 when I bought it. Years later I came across a few memory sticks and popped them in and gave the thing 16MB of ram from 8. The game started nearly instantly and ran very nicely (usually took 3-5 mins to start). With 8 it was choppy city and slow. Exact same computer only diff was the memory.
If memory serves me they did not really change much in NT from 4.0 to 2k. Other than add in more services and make it more win98 like. So it is maybe not an 'unfair' comparison. But win 3.51 came out getting that sort of computer just would not be in the cards for most people.
Windows went sideways at vista. The 'start the computer up' out of the box would use 2-3gig of ram. Up from 100-200MB from the XP era. Toss in some corp bloatware items. One place I saw it was 10gig just to open the desktop no productivity software even started yet. Then add in the zillions of indirect layers we have added to make programming easier and we are now with applications that seem to start at about the same rate as 25 years ago.
All of those old API's are still there. No one really uses them much anymore. We use the latest cool frameworks. That use the previous cool framework that eventually uses the old APIs :)