From what I gathered off of several HN comments of Uber insiders, the size of their engineering team is actually more likely to be one of the causes for bad engineering decisions. They seem to have too many engineers running around for too little actual work to be done, which results in those engineers coming up with stuff to do to keep them busy (and of course to ensure they appear to be busy and worth their money to their superiors).

One of the best ways to create yourself some work is to not choose an already-proven path to a solution, but invent a new one just for the sake of inventing a new one. Of course that's not how this kind of doing is justified - the justification is usually "the proven path does not scale to our needs" or "by using a special approach adapted to our needs we can be more efficient" or "the proven path is too complex, we can get by with something simpler and easier to maintain". Which might actually all be proper justifications, it's just that you should have some hard proof for these statements, like benchmark results of a comparison of different approaches. That part often gets skipped, which is actually ironic, because doing extensive evaluation and benchmarking and implementing different approaches first before choosing one for production actually serves quite well to create even more work to do.