The labor force participation rate is at its lowest level in 40 years. When companies like Homejoy come in and make it easy for people to pick up gig work, they are making real and substantial contributions to human welfare.
That's a much more complex issue, which involves how many people simply give up trying to find work after six months or so, as well as companies replacing employees with automated robots and such. I would be much more in favor of Homejoy using contractors if they also allowed them to become a full time employee if they desired to, after meeting some requirement (like working there for 3 months).
But the convenience increases the size of the market, benefiting both customers and laborers.
I never ordered from a cleaning service before Homejoy, and I doubt I'll bother with it after Homejoy. It's a useful service to me, but I'm not going to call half a dozen random guys on their cell phones to find one that will work for me.
Similarly, ride volumes are way up after Lyft and Uber come to town. Before, there is a lot of demand that is simply going unfilled.