I think more of the business potential of these companies require bad things compared to other companies. Most companies have some sort of core business and the things that in part end up being bad for other are second to that. With DIFM companies those things, at least almost, ends up being the core business.

https://www.uber.com/jobs/list

(of course the sector of businesses we are talking about isn't very well defined)

The problem is mostly that these companies seem to try to put a wall around a market and try to become the gate-keeper for that particular market, and will then become the regulator of that market. This goes against the principle of "free markets".

Besides these "do it for me" markets, roughly the same pattern is seen with app-stores, and probably many more markets.

(Of course, in a truly free market it should in theory be possible to create such nested markets, but this just shows that the concept of a totally free market is nonsense, and that we should act against these patterns.)