Dude, they get to contribute to the company for free.
I'm sure the OP means well, and it may have been a success for them, but I don't know anyone in my circle who would participate in something like this, unless they were utterly desperate for a job. I thought there was a serious talent crunch? Who is courting whom?
I wonder what sort of engineers self-select in a process like this?
Unemployed people have lots of time. Understand that and you'll understand why a weekend like this makes sense.
One reason they're unemployed is that they don't know how to demonstrate their value. A lot of engineers are actually poor at communicating, and not that great at resumes.
This weekend was for them.