While it's a worthy question to ask, it's not applicable to them outside of theory, since they have been using PHP since they started some years ago. If you rep

While it's a worthy question to ask, it's not applicable to them outside of theory, since they have been using PHP since they started some years ago. If you rephrase the question to a company just starting out, then it would be more fitting :) If you look at the larger companies that do switch platforms, the ones that generally make the leap usually do so without replacing the entire stack (Java to jRuby or Java to Scala, etc). Not always the case (since the language can still be hurdle itself), but the cost to switch in those sort of cases is far lower than jumping off the jvm/clr/etc. I'm sure if you asked Facebook now (and got an honest answer) that they would totally agree they would have picked another language and platform than PHP to build on given what they have had to go through since. However, PHP is what the developers knew starting out and sometimes it's better to go with what you know than learning something entirely new as building something from scratch is already a huge undertaking that can wear you down. Adding the burden of learning a new language/platform at the same time can lead to taking on too much and slow progress/motivation as well as lead to procrastination or distraction. It might lead to regrets later, but the greater regret is not building at all than choosing the right platform.