How does functional, side-effect-free code increase complexity? What makes your side-effecting code more testable and verifiable than unambiguous in/out functional transforms?
With jQuery and such you just include a script and back then there were no package management system, glup/grunt, webpack, yeoman/brunch, etc..
Also the client side rendering make SEO hard.
jQuery just get stuff done but at the same time the organization of your code is up to you and you do sacrifice some reusability but in general the trade off is complexity.
VueJS as much as I love learning this framework, it is complex with webpack, cli, browser plugin, and etc...
"Just get things done" when the way you're doing so is less clear, less testable, and less reliable is not, to me, the hallmark of a developer I would trust with anything I cared about.
If your project is simple, webpack setup is copy/paste (v3) or no config at all (v4). If your project is doing complex stuff, webpack is more in-depth, but a breeze compared to the make files and XML config of other languages. More importantly, webpack has a very clear tutorial and extensive documentation. You have to go incredibly far off the normal path to run into something that isn't covered. Off topic, but augmenting webpack dev server express instance made dev work many times easier on my current project.