I strongly believe you can build web applications without having to pull in Gulp or Grunt. And to back up my claim I setup a project [0] that shows how to do it using webpack + npm run-scripts.
I'd argue it solves a large set of problems while maintaining a reasonable level of complexity.
I ignored Grunt for years, always implementing my own hackneyed systems in Python, until I eventually discovered this tutorial[1], which at least got me a good introductory "this is how you use this thing that everybody else already knows how to use, dummy" lesson.
Yeah they did kind of just sneak up about a year ago it seems. I remember getting into the field two years ago I didn't hear about them. I suspect the tipping point was the full migration to front-end frameworks instead of just plain JS/jQuery.
Now, to be fair to Grunt, my workflow is usually Python or Go on the backend, and I just wanted something to manage my front-end assets, so it was never a necessity for me, but knowing there's something that does what I want it to do, while being unable to make it do the thing that it does is quite frustrating.