> Now imagine an editor like Neovim, but instead of working through 30 years of cruft and legacy code, it's built from the start using modern software engineering techniques and incorporates such features into its core editing model.

User inertia is strong. Neovim has its success because of its improvement, but more importantly, the keymap and config language is based on Vim7. Vim7 users can painlessly switch to Neovim with all config preserved. That's the main reason why Neovim can gain a large number of users initially. Conversely, Helix has no keymap nor configuration compatibility with Vim or other mainstream editors. Given this, I see no hope that Helix will become mainstream.