The problem is software, though. I have a X200s with 4 GiB RAM from 2009. It was interesting to see how Firefox got slower and slower over the years. Granted, it not only is Firefox but also retard websites which use loads and loads of JS to display static content in the end. In return, it is not like JS didn't exist back then: The XhtmlRequest thingy for dynamic website updates or whatever the name for that was has been added years prior to that.
So, yes, a lot of this comes down to software and a massive waste of cycles. I remember one bug in Electron/Atom where a blinking cursor caused like 10% CPU load or something along that line. They fixed it, but it tells you way more about how broken the entire software stack was at that time and it didn't get better since then.
I mean, think about this: I used 1280x1024 on a 20" screen back in the mid 90ies on (Unix!) machines that are insanely less powerful than even this X200s. The biggest difference: Now you can move windows around visually, back then you moved the outer frame of it to the new place and then it got redrawn. And the formatting options in browsers are better, i.e. it is easier to design the layout you want. Plus there is no need for palette changes when switching windows anymore ("true color"). The overall productivity hasn't kept up with the increase in computing power, though. Do you think a machine 100x the performance will give you 100x the productivity? With some exceptions, the weak link in the chain were, are, and will always be humans, and if there are delays, we are talking almost always about badly "optimized" software (aka bloat). That was an issue back then already and, unfortunately, it didn't get better.