I'm surprised you are comparing jQuery (a non-trivial additional dependency with reasonable dependency-less alternatives) to printf (a small piece of a dependency you most likely pull in already with).
One man's trivial is another man's bother. I consider 30k (less than some images or the rather popular fonts) to be quite trivial for most purposes, and if it gives me a nicer syntax for common operations, it's probably worth it.
On the other hand, I've seen actual backlash against printf implementations in libs and the bloat they're causing, never mind potential bugs [1].
I'm not advocating for or against jQuery or printf. I'm just pointing out that equating the two (in size, utility, or potential gains by avoiding them) doesn't make a lot of sense.
jQuery's ratio of size-versus-additional-utility is much larger than printf's, even more so if you consider typical use cases of each.
But it isn't even a fair comparison to begin with. How about comparing jQuery to libc. I'd still argue the ratio is in libc's favor, but no one would have written "I'm surprised that there's no youmightnotneedlibc.com".
libc seems much more substantial, maybe we can split the difference and call it "youmightnodneedstdio.com", although that sounds much less pithy.
I still wouldn't be so sure about that ratio. The people decrying the printf family of functions are often targeting small statically linked binaries. Where a few kb shaved off might be a bigger chunk than 30kb are for your usual multi-megabyte front page of today's web.
It would have been if he said "I'm surprised that there's no youmightnotneedlibc.com".
As soon as you do that though (put the two on equal-ish grounds), you realize it doesn't make much sense and it might as well not have been written in the first place.