This is people idealizing things. In best of world, yeah, who wouldn't want to take units[1] of work at will. Have some available time? Put in a bid, do the task and be done. On the other hand, as one can see with Uber on the one hand and 1099s on the other, it's a mixed bag with lots of pros and cons. You manage your own time, but you take on more responsibility. I think, given the realities of life, people will, on balance, choose the stability an FTE position.

[1]this isn't always practical as many things are not inherently divisible into units of labor [pregnancy being the iconic example where you can't put 9 women to deliver in one month]