Boiling down some of his points on the problems with common lisp that made him switch away from it:
1. Editor support. The original poster bemoans that the only fully supported editor is emacs and that there is not sufficient support for neovim. I have used emacs and slime, but I had to stop because of the ulnar tunnel syndrome it was causing. But I knew vim before I learned emacs and I am a neovimmer myself. I have used jpalardy's plugin[1] for many years and couldn't be happier with it. There's a visible repl built in, so by definition it's fully featured. The reason emacs is the only editor for lispers is that it tries to be the whole operating system. It turns out using a terminal multiplexer along with an editor gives you everything you need. I like GNU screen on Linux and ConEmu on windows.
2. Community. The original poster speaks of toxicity and a community full of people who are not welcoming to newcomers who ask simple questions. I'm just barely starting my Common Lisp journey so I can't speak to that. But I don't know if I'm discouraged by a community that values members who are capable of doing their own research and not needing their hands held. I'm often surprised by developers who need YouTube videos to explain to them how to do their job as if they can't read their own code. Maybe that's why the documentation is so poor in the Common Lisp community: the expectation is that you can read their code and figure out what it does. The original poster says that the community is full of people who do not wish to work with others. That makes me feel like if I write in this language I'll be able to be productive even if no one else wants to work with me. I'm not hugely popular and don't have a ton of stars on my GitHub pages, so the idea of a language that allows me to be productive even if no one else wants to help sounds pretty good to me.
3. Packaging. The original poster speaks against packagers who take responsibility for the cleanliness of code before it gets packaged up for the quicklisp dist. He complains that packages are released on a monthly basis and that this is not fast enough for him. As a DevOps engineer, I think this is fantastic. I hate it when developers release code too frequently because the new releases often break things even when they are not intended to, and reacting to those changes takes time. A little bit of time before each release is easier on your consumers. I feel like the best sweet spot is 90 days. I'm getting killed at work right now because of the breakneck speed of helm chart packages and how fast they release completely breaking changes. I also consider that the absolute best packaging community on this planet is Fedora and Debian operating system packages. The idea of having a separate packager from the actual software making sure that the software lands well and plays nice with its neighbors is a huge feature of those communities. Those operating systems wouldn't be possible without them. The original poster also complains that there is not any versioning. If this is the case it is very sad to me and I hope that somebody can refute this claim.
vim-slime does not connect to any Swank server. It does not understanding Lisp s-expressions. It would happily copies any random text into any random REPL and call it job done! Lisp interaction mode is much much more than just copying and pasting text around. A superior lisp interaction mode gives you live debugging, handling conditions, inspecting variables, navigating the stack frames, ... Vim-slime cannot do anything like this because, well, it is not SLIME! It just copy-pastes stuff around. Vim-slime is a disingenious and misleading name for a project that is not SLIME.
If you really want to use Vim, do yourself a favor and use https://github.com/kovisoft/slimv and experience a true Lisp interaction mode. It contains an actual Swank server and an actual Swank client that connects to the Swank server to provide an actual Lisp interaction mode in Vim just like SLIME does in Emacs!