Earlier quoted context omitted.
So what does this mean?: "In order to encourage folks to use native JavaScript functionality and keep their project as slim as possible, this year we’ve chosen to remove JavaScript libraries from the “free resource” camp."
You could previously include JS libraries and they didn't count against the 10k limit. now they do. EDIT: Somehow, since lazy-loading not strictly required stuff apparently doesn't? ( https://a-k-apart.com/faq#size )
You can lazy load libraries for sure. I would still keep those to a minimum, including only what you need. For instance, don’t load all of jQuery if you only need one feature. And use native JavaScript code when you can get away with it—dataset instead of data(), querySelectorAll() instead of $(), etc.