Let's not forget Bram Moolenaar, who also deserves credit for extending the work on Vi. Vim [Vi iMproved] is likely (along with NeoVim) the actual Vi editor most people are using these days.

What's the story with NeoVim exactly? I am trying it out on Linux because I got some recommendations that it's better than Vim, but I've run into some problems because for instance with setting up plugins and things, lots of times the documentation seems to be geared toward Vim, and sometimes I've gotten errors it's hard to figure out because of this.

It kind of gives me the perception there just aren't that many people using it, so it might be one of those tools which is technically better but doesn't have the critical mass of community to really be useful.

Am I off base there? I mean what are the tangible, user-facing advantages of NeoVim over Vim?

https://github.com/vim/vim - 20k https://github.com/neovim/neovim - 36.5k

This is in some part due to the fact that neovim has been on Github longer, but it's still a a major indicator.

Neovim has many benefits over Vim, and has been applying pressure on Vim for years to improve its own development and codebase. Nvim has first class support for Lua outside of Vimscript, which has enabled a lot of people to write more powerful plugins. A lot of NVim's featureset has been copied into Vim over the years (one of my favorites is the hover window, which has allowed IDE like support for code references/comments/source). Supposedly, Nvim's codebase is significantly easier to maintain and contribute to, due to the nature of having a community of contributors that built it from ground up, as opposed to one primary developer working on Vim.

The parity has reduced over the years, but Nvim has been significantly ahead in pushing new features and active development over Vim resting on its laurels.