I agree. Funnily enough, though, the upgrade pain to 9+ had nothing to do with Jigsaw, because its encapsulation hasn't even been turned on (unless you count warnings). It was just the biggest and most visible change, so people blamed their unrelated upgrade issues on it. The actual cause for many issues was that some popular libraries hacked into off-specification, undocumented JDK internals and relied on them (Groovy did that a lot), and they simply changed, as they're allowed to. The most disruptive specification change was actually dropping the "1." prefix from the version string, that many codebases used to parse.

Starting with JDK 16, Jigsaw is finally being fully turned on, and is starting to block access to internal JDK classes unless the application explicitly allows it. Ultimately, this will force libraries not to rely on internal implementation details and so get themselves tied to a specific version.