I think the goal here is to avoid needing something like react query. The loader functions you write execute on the server and pull data that is needed by the component.

You can of course still use react query/swr/redux tool kit etc if you want. Remix doesn't limit what you can do and still fully supports any of these and other client side tools.

Remix just encourages to make better use of server side code instead of shoveling everything into the client.