So google compute setup I did a while back with preemptible instances + a celery queue + some autoscale based on load...
The guts to make all that work was 50 or so lines of config. I think my auto scale script was 20 lines or so of Python.
I guess the biggest downside was spinning up the new server took about 2 minutes, so for big load spikes it took a bit for it to level out... but with GCE per minute billing, all the napkin math I did says it is a fair bit cheaper per cpu unit to do it this way.
In conclusion, someone good with devops + a normal work queue system could do this years ago. I guess it's cool to lower the barrier to entry, but not it does not seem like a game changer. It totally IS cool to scale out backend work to a job farm. Just seems like not the only way to do it.