WordPress right now theoretically support upgrade from version 1.0 straight to 4.9. I assume this code was never actually tested and in the name of not having untested code in our code, we need to limit upgrades to a time range we are going to actually test, or at least support and fix bugs when they are discovered. Being able to upgrade from any release to any release is just not maintainable in the long run.
WordPress right now theoretically support upgrade from version 1.0 straight to 4.9. I assume this code was never actually tested and in the name of not having untested code in our code, we need to limit upgrades to a time range we are going to actually test, or at least support and fix bugs when they are discovered. Being able to upgrade from any release to any release is just not maintainable in the long run.