The possibility to add custom language servers in configuration only

[eproxus]

When trying to understand the documentation regarding language server configuration, I kind of guessed that something like this should be possible:

    "languages": {
        "SQL": {
            "language_servers": [
                "sql-language-server"
            ],
        }
    },
    "lsp": {
        "sql-language-server": {
            "binary": {
                "path": "sql-language-server",
                "arguments": [
                    "--method",
                    "stdio"
                ]
            },
            "filetypes": [
                "sql"
            ],
        }
    },

However, Zed just reports this in the log:

[WARN] no language server found matching 'sql-language-server'

There are also some documentation and a lot of comments suggesting custom language servers has to have an extension for them to work.

Why is it not possible to add a custom LSP configuration that uses an external binary? Isn't that the promise of LSP, that you don't have to implement custom support in each and every editor?

Is it simply because Zed doesn't have any support for this (e.g. in contrast to Sublime LSP or other editors) and only has a model where it requires extensions?

[SomeoneToIgnore]

Is it simply because Zed doesn't have any support for this (e.g. in contrast to Sublime LSP or other editors) and only has a model where it requires extensions?

Precisely.