The OP's initiative may come at an excellent cost-benefit price, but it's questionable whether they even considered the tradeoff. And if they have, it's still important to discuss it if it comes to an internet forum.
" Now, could I have finished it quicker and moved on my way if I’d just done it myself? Of course. But that’s not what it’s all about as an open source contributor. It’s fun delivering good software that helps other people, but also realize that there are tons of people out there who just don’t know where to get started.
Some of you may be asking yourself, “what if I (and other lib users) don’t want to wait days for the feature?” From my experience, people are eager to try it out. At least one PR (sometimes several) is submitted, iterated on, and merged within a matter of a few hours. "
Clearly, productivity was not a priority.
I mean, it's very well possible that the long-term investment in expanding the "base" of willing coders is worth the short-term loss in productivity. But even long-term investments in human capital need better planning than just "hey, I bet a high-schooler could deal with this simple accounting spreadsheet; that would train him even if it takes him a day to fix what I can fix in ten minutes". It's fine investing in high-schoolers, sure, but that's not the point.