Not only because of price. The 'ecosystem' infrastructure wasn't there, or at least not spread wide enough. The 'mindshare'/thinking of ways how to do, neither. This is more aligned with (live) 'image-based' working environments like early Lisp and Smalltalk systems. Look at where they are now...
A few more thoughts about that, since I happen to have some of the last systems who actually had systems level support for that in their firmware, and early low-capacity optanes designed for that sort of use. It's fascinating to play with these, but they are low capacity, and bound to obsolete operating systems.
Given enough RAM, you can emulate that with working suspend and resume to/and from RAM.
Another avenue are the ever faster and larger SSDs, in practice, with some models it makes almost no difference anymore, since random access times are so fast, and transfer speeds insane. Maybe total and/or daily TBW remains a concern.
Both of these can be combined.