It isn't obsolete. Webpack just reduces task runners even more, since webpack takes care of taking your source, copying your source to your build/dist/whatever directory, minifying everything, creating hashes in filenames, being able to update html with those hash names, etc.. Basically, if you can use `import` on a file in Webpack 2 or `require` in either Webpack 1/2 you don't need Gulp/Grunt to do that work.

I personally work on things that still need other aspects of the task runners.