[jlukic]

These utility functions and shims are "per" component. This means that functions like extend will be repeated many times in different idiosyncratic code across app.

Imagine your app uses, modals, dropdowns, multiselects, search autocompletes, sliders, rich text areas etc. Instead of having one cached utility library upfront you have many hidden utility libraries scattered around each component, which makes it difficult to say clearly that jQuery is always larger.

The other issue is maintainability. When you're working with third party components, hot-fixing an OS library can be fairly daunting if you need to also learn their own internal class structure, selector helpers, dom manip functions. Doing this in jQuery, it's fairly easy to fork the codebase and plop in a .clone() or .append() to fix a stale issue.