Bram is consistently updating vim and recently shipped 9.0 which introduces Vim 9 Script. I would say that there is a line being drawn in the sand more distinctly now, though. Those that adopt the new vim script will probably stick with vanilla vim and neovim's team has no plans at this time to support it [1]. And all these lua plugins are only compatible with neovim.
[1] https://github.com/neovim/neovim/issues/13625