That is true. But some companies got it very, very right. They made software that has stood the test of time.

The same can not be said of present-day stuff, which seems to change on a weekly basis. I don’t know how anyone will ever be able to use the old Facebook again once they shut it off.

Weekly? Several times per day. Mind you, I'm going with the flow and I'll be more than happy to do things that way too, it is the competitive arena we live in and if you can't fight them join them. But I do feel that the code I wrote in the past was more mature, higher quality and had more longevity in it simply because the pace wasn't so idiotically high.

Isn't that just survivorship bias? The old software that survived either had massive lock-in or was good enough to survive. In another 20 years, some software from today will survive, and that too will be the stuff that was big enough, caused enough lock-in, or was good enough to stand the test of time.

It is and it isn't. My point is that back then it wasn't possible to update software continuously. Thus, the development model was very much focused around putting out discrete, fully functional versions.

Today that isn't the case. It's all about continuous rollover. So in 20 years the software that "survived" will be the same old software that we're talking about now (from the 90s and earlier). All of the present-day software will be continually updated and may be unrecognizable in 20 years.