It definitely doesn't excuse anything, but I am somewhat taken aback by how badly priced those commissions were. I would be shocked it an artist didn't burn out and bail after making >$5/hour, especially since they allowed bulk commissions like this beware.
I think there's a fair lesson to be learned from both parties here- the artist probably got way in over their head with commissions and made a mountain of work for scarce compensation, and made the poor choice of ghosting instead of finding a solution. Hopefully not a mistake they'll make again. Even better would be refunding OP after all this time, but I doubt it'll happen at this point. Admittedly, this is a lot of speculation/assumptions and assuming the intentions weren't malicious from the start.
And OP can learn a gentle lesson about not diving headfirst into deals that seem too good to be true. Best case here, an artist makes pennies for their hard work and you get a killer deal on art. Worst case, something like this where you never even get said art. I would just ask that commissioners take some more consideration for artist's time with things like this; even if the artist is readily offering to work for so cheap, maybe have moderation and only get one or two pieces, possibly even with a little tip added for their time.
Not meant to be a criticism on OP or to misdirect the post's attention too much here. Just 2 cents from an empathetic artist who's been in the, "Crap, I should NOT have agreed to that price" situation far too many times. But needless to say artists shouldn't just ghost when that happens, so beware well warranted of course!