> For a compute-intense task
The browser often runs on an immensely powerful computer. It's a waste to use that power only for a dumb terminal. As a matter of fact, my laptop is 6 years old by now, and considerably faster than the VPS on which our backend runs.
I let the browser do things such as data summarizing/charting, and image convolution (in Javascript!). I'm also considering harnassing it for video pre-processing.
You can take advantage of that power via WebGPU, or WebGL if the browser is not yet up to it.