I think it is worth discussing the counter arguement.
My team supported Windows from XP to Windows 10. I continued to be staggered at the backwards compatibility of it. I remember having an ERP client that was written in VB6, and nobody thought it would run on 7, but it did. Everyone assumed it was obvious it wouldn't run on 10...but it did... with less RAM usage and it was a bit snappier. Same with the ancient copies of WordPerfect and Photoshop (old enough that they came in a box).
I had a mixed fleet of machines from very old to very new and Windows 10 ran on all of them. I bet it would run on this guys P4 just fine. That is extraordinary isn't it? MS have a current commercial OS that will run on 30 year old hardware!
Before we criticise MS too much, let us compare that to other commercial providers...like Apple for instance. How much of your 1990's software runs on the last gen Intel Macs even? Answer is...none, isn't it?