For $client we've taken a very minimal approach to JavaScript, particularly on customer facing pages. An upcoming feature finally replaces the last jquery (+ plugin) dependent component on the sales page, with a custom implementation.
That change shaved off ~100K (jquery plus a plugin removed) and for most projects now that probably seems like nothing.
The sales page after the change is now just 160K of JS.
The combination of not relying on JS for everything and preferring use-case-specific implementations where we do, means we aren't loading 5 libraries and using 1% of each.
I'm aware that telling most js community "developers" to "write your own code" is tantamount to telling fish to "just breathe air".
Updating dependencies is a task a person does, followed by committing the changes to the repo.
I am aware a lot of these ideas are heretical to a lot of software developers these days.