I was leaning (in principle) towards agreeing with you both - I tend not to trust anything I didn't make myself, cos i know what goes where and I know how it all fits together and how/why it works
but then I considered tools, I didn't make my welder, I didn't make my electric drill, I didn't make any of the spanners I have (and a spanner is simple, I could make one)
and I could extend that thinking to my PC, I'd claim to have built it myself, but did I really? or did I just assemble a bunch of stuff others had made? - It is mine, there is no other exactly like it anywhere, but I really didn't actually make any of the bits inside
so, maybe trying to see this jQuery thing as another tool, not really so different to the keyboard / mouse / screen / HD - though a software tool rather than a hardware thingy