[umbs]

"... vim and neovim merge,..."

This seems very unlikely. In neovim help docs there's a paragraph in file `nvim.txt`

   Nvim is emphatically a fork of Vim, not a clone:
   compatibility with Vim (especially editor and Vimscript
   features) is maintained where possible. See |vim
   differences| for the complete reference of differencesfrom
   Vim.

nvim maintainers believe the project diverged and compatibility is best effort at this stage. Essentially, there's no plan to merge the two projects at this stage and the benefits are not evident.