Why do so many online image tools still require uploads?

I've always wondered why so many image resizing and compression websites still require users to upload files to their servers, even for simple tasks.

With modern browsers supporting Canvas, WebAssembly and client-side processing, it seems like many common image operations can happen locally.

Is it mainly because server-side processing is easier to build, or are there technical limitations I'm missing?

For those building developer tools or browser apps:

• Have you tried client-side image processing?

• What challenges did you run into?

• Where do you think server-side still makes more sense?

I've been exploring this while building an image-processing project, and I'd love to hear how others approach this tradeoff.