Unity isn't the problem. The project management and developers are.
This is generally the case, tools do matter, but people matter much more.
Give a brilliant team a conference room and a supply of paper, pencils and food and they will turn the world on it's head. Give a team of idiots the best tools that money can buy and all you'll get is a steam pile of fertilizer.
(Give the brilliant team the best tools... though, even if it only makes them 1% more efficient it's still cheaper than the tools.)