1) That market success implies having quality software. Average seems to be enough in my experience.
2) That start-ups are a good example to follow if one wants to achieve good quality. In fact they should be ignored, because they will absolutely murder quality in order to stay alive. Sometimes the product doesn't even work and is held together with duct tape in order to get past that important demo... It's quite pointless to discuss quality and start-ups.
The lesson I mentioned should be heeded by mature companies that are able to do some project planning, complexity estimation, etc.
It seems that this same pattern plays out with many tools, and not just languages. When you've built something and you now have a team, processes, etc. built up it becomes difficult to see the forest for the trees, or to make the hard decisions because it might involve replacing people.
Yeah, absolutely, don't do this! These are two examples of successful companies that did it and look at them now! </s>
Being able to move fast and produce a winning product on time is much more important for startups. What does it matter if you used <your_cool_scalable_thingie> for a project, when it never went past 10 users because you were concentrating on wrong side aspect of your business? PHP is fine. Python is great. Use the tools that fit your problem and you know how to use, not the latest toy.