I swear that my initial reading of the title was "74 Decades Later", and I smiled because it fitted the feeling of how late this addition is arriving. Then I realized it'd be a bit strange that they used this kind of snarky sarcasm on their own blog, and had to re-read again the title.
Also,
> This is the culmination of more than a decade of work, and was only made possible by GTK4’s complete rewrite ...
read to me as
> this (lack of an essential and basic UI feature) was only caused by the typical "let's rewrite everything" movement that started more than a decade ago
I know HNers are very sceptical of the technical merits (or their lack thereof) that ground-up rewrites usually have. I only hope in some years, GTK 5 or 6 doesn't decide to trash all this work and starts from scratch again.
Regardless, my congratulations to the people who pushed through and contributed their effort to make thumbnails back!