It's neat old Mac's from the 80s could to do that...but they had to be able to do that in order to be useful. In other words, it wasn't a "cool feature", it was something they had to be able to do.
I imagine that when storage became more plentiful OS developers became less interested in implementing solutions to problems of this nature and who can blame them really. Supporting a use-case that almost no one cares about anymore is rather unrewarding.
As others have mentioned, there are plenty of ways to achieve this on Linux today, they just seem to involve more fiddling than you'd like. That, unfortunately, is the nature of the beast.
Linux is a tinkerers OS (that just happened to become popular for servers) and expecting it to change its stripes is asking a lot :-)