Again, I agree with everything you have said in your post. The main thing I do not like about upwork is the fact that they bought or took over elance. Even thought elance was a much smaller network than what upwork is now, elance had a simpler interface, you would know a little more about the client and you had a little more control as a bidder. Also the fee was just under 10%. To me it seemed like upwork didn't like the competition from elance and did a corporate take over and in the end we have an inferior product. That being said, I looked around for other alternatives and can't find anything much better. . I have not had the same success with upwork as I did with elance, which was not much to begin with.
BTW, I do mechanical design engineering work Great post, Uv & Rs.