The argument against this is the cost of a user's bandwidth. If I have all the computation done on the server side, then I have to wait for the round trip every single time just to download the results. In this case, the browser's compute is more free, as the cost to send a remote request is more than likely higher.
Like most things, there is no simple right answer, and it depends on what you are doing. But blindly assuming the experience will be worse using CSR is as silly as assuming SSR will always be worse as well.
