To my knowledge, besides the newest updates not necessarily being as stable, but also, other softwares that interact with it would need time to adapt themselves to be sure they’re as compatible as they were before. In a situation of constant updates, other software would always be on a situation of catching up, whereas updates that take a bit longer to land allow “for the dust to set down”.
On the joke, define “sane”. 😬
On a serious note, I think there are valid reasons to have several VMs other than “I was bored”. In my case, for example, I have a total of 7 VMs, where 2 are miscellaneous systems to test things out, 2 are for stuff that I can’t normally run on Linux, 2 are offline VMs for language dictionaries, and 1 is a BlissOS VM with Google programs in case I can’t/don’t want to use my phone.