I'm curious why supporting ML algorithms is important inside browser ? Will my machine be improperly utilized by the sites I visit ?

It can absolutely be used for bad, and I know many sites do use it for bad. However, it does good as well, and I think it's important to develop but also it should come with similar permission requests that use of microphone or camera do.

I do research and develop ANN's for data analysis within chemistry. Making it possible for less tech literate people to visit a site, select a model, load their dataset, and get answers, is quite handy. The best part is because I can use their hardware to do it all, it all stays private, no one has to upload any sensitive research data etc. and I don't have to ship to various devices etc. I know if they have a mainstream updated browser they can likely use the tool. No endless requests for help, no mystery issues to solve, things just work.

We've already seen Javascript cryptocurrency miners, so when WebGPU starts actually being used I suspect we'll see their use rise to new heights. It's a matter of time until some website starts offering WebGPU crypto mining as an alternative to their paywall.

Lot of downvote for my curiosity