This is the "silent killer" for legacy software.
Adobe has never made a perfect version of Illustrator. They have only made different versions. For those who value muscle memory and stability over generative AI, the "old version" isn't a bug—it's a feature. adobe illustrator old version
The biggest danger of using an old version of Illustrator is compatibility. If you design a logo in Illustrator 10 (from 2001), you can open it in CC 2025. However, If a client sends you a modern .AI file with cloud fonts and gradient meshes, opening it in CS4 will result in a grey box and an error message: "This document was created in a newer version of Illustrator." This is the "silent killer" for legacy software