I'm not a regular Zed user, but this isn't true: I simultaneously ran the Ruff and Pyright LSPs when I used it last week.
In my currently opened project I have: vtsls (for typescript), biome, emmet, and the snippets LSP running on the same file.
You can configure which LSPs you can run on a language basis. Globally and per project. You can also configure the format on save actions the same way. Globally and per project.
I have astro project that on save runs biome for the front-matter part followed by prettier for the rest.
I would say that's pretty flexible.