[karthink]

> Something this old shouldn't have this property.

It's not an accident -- reading through the emacs-devel mailing list, it's easy to see how much effort the maintainers pour into backward compatibility. It's one of Emacs' unspoken guiding principles[1].

At the same time, it's not that surprising either. Emacs does not have other objectives that more modern languages/ecosystems do: no revenue or growth targets, corporations or VCs breathing down its neck, or a mandate to be "modern". Its most vocal and experienced users, who are also its volunteer maintainers, decide what its priorities should be. Since they've been using it for decades, backward compatibility is high on the list.

[1]: It's "spoken" guiding principles being to further the goals of the GNU project.