[pydave]

I'm not so sure.

Neovim migrated to a more modern style of C and more tightly integrated Lua as its scripting language (instead of conscript). Those are two large potential stumbling blocks for contributors.

From loosely following development over the years, I see names like chrisbra and justinmk who contribute to both projects, but there seem to be many who contribute to neovim but never contributed to vim.

Neovim also seems to have influenced the development of vim: channels, jobs, terminal mode, and issues/PRs on github (instead of mailinglists) felt like shifts in response to neovim.

I think it's also to Bram, justinmk, and other maintainers credit that the two projects contribute back and forth: many vim fixes are merged to neovim and I see big changes get brought back to vim too.