There probably are reasons. They may not be technical and they haven’t explained them. But that doesn’t mean they don’t have a good reason, from their perspective at least.
There’s been plenty of discussion and theories on this forum as to why for years. A popular one seems to relate to the data (about you) they can collect if everything is cloud-based and then sell. But that’s just a theory as far as I know.
Either way, this is not a new issue, it’s been baked into ST since they were funded on kickstarter.