I think one of the mistakes of the Ravenloft setting as a whole was trying to make it have a "continent" with fixed borders. If you're in a weird demiplane, then it would be far more practical to have each realm be in its own space, and travelling through the mists would not reliably take you from one nation to the next. It would then have been random or up to the GM where the PCs moved/fled to.
I really like the idea of a patchwork map. A significant amount of consistency keeps the weirdness but prevents Ravenloft from just becoming another Astral Plane, where everything is next to everything else. And once that's established, it makes sense within the setting as well. Realms may break off and the Mists may not always be reliable, but explorers are still going to try for their best guess at a map.
IIRC from comparing and contrasting the two 2e TSR box sets it was each a part:
a) keeping it different from the Astral as it is the Deep Ethereal and needed at least some narrative cohesion for its romanticised gothic horror (basically more grounded sense of space, less delirium or disassociation),
b) the realms were once more isolated and/or nebulously tied to each other before, but were becoming closer and more reliably tied together during the lead up to the Grand Conjunction -- basically a meta-narrative crescendo of six adventures which *could be* played in a specific order to affect its trajectory,
c) and it gave cause for the Dark Lords to target one another in an effort to get free or get intel or just general expansion of their crapulent personalities. This provided two things: an easing up of Dark Lord focus upon upcoming heroes to rub their nose in their Dark Powers' punishment again, and opened a metagame arc for cross-domain adventures beyond 1e's typical "weekend in hell."
Whether that was all communicated quickly enough to users is another story.
But overall it was a priority shift to do larger things with the property as a cohesive patchwork setting. Again, not hard to ignore and revert back to form, let alone shuffle around which you are invited to do, (except cautioned about some effects to the Grand Conjunction six-adventure connected arc, if you care).