They can be easier to get started with than just installing Neovim from scratch. But they add their own complexities. First, you have to know that they exist, and pick one. Then you have to know how to configure them, they may have their own nuances about how things are done. Under the hood they're using all the same packages, so you'll need to learn how to configure those as well if you don't want the defaults.
I would say the distributions to make it extremely easy to get started with a functional IDE experience with LSP features. But they're not without their own learning curve.
Also it might be the fact that vim was never my main programming tool when IDEs were available for the programming task at hand. I debug as much as I write code, so having the debugger in the same context is important to me.
These things may all sound like excuses, but what I'm trying to convey is that vim can be a tool with which someone is proficient, but it's not the main one for writing code, and as soon as friction gets higher, it gets disregarded in favour of something else.
If someone is new to vim, I 100% agree that it's easier to get started with VSCode/Jetbrains/etc.
But if someone has been using vim for a long time as their default editor, especially Neovim, and when LSP support came to Neovim about 4 years ago [0], it comes across as someone who isn't a power user if they didn't end up installing it. Which is fine, but the community has also started to build reasonable "batteries-included" distributions of Neovim (LunarVim is a great example) if someone didn't want to figure it out themselves but still wanted to use it.
It's one thing if someone just doesn't love the experience Neovim brings to them. That's reasonable, because it's subjective. But it is odd to use a tool for so long and not further investigate what it offers to fit your needs. Before LSP, there were libraries (CoC for example). And if it was never satisfactory, why not look at alternative editors which had their own flavors of indexing/code navigation?
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[0]: (https://github.com/neovim/neovim/commit/a5ac2f45ff84a688a094...)
As a similar example, I could never be bothered to install and configure any LSPs even though I've been using vim for more than a decade. The friction of doing that was always just a little bit higher than installing a full blown IDE when the work actually requires high level LSP functionality.