The choice of language is never irrelevant. Especially if you are launching a start up. You are about to build the foundation of your future development architecture.
For example C++ is a great choice for heavy data processing and number crunching, but horrible when aggregating multiple web services or building HTML. PHP is like the opposite and Java is a poor choice for either (imho).
Also you will need more developers later on who fit into your working culture. Good C++ devs are likely slightly older than your average NodeJS-Hacker and they care about family and such non-work-related stuff.
Haskell guys would probably stay for some late hours to discuss wether their new typeclass is just satisfying a semigroup or fulfills all monad laws…<p>My advice: choose a well adapted language from the field of industry you aim for: general web/e-commerce - NodeJS/TypeScript, automotive/industry/embedded - C++, finance - .Net/C#/F#, Science: Python
Okay, choose your back-end language randomly.<p>I suspect you are wrong, and that the differences <i>are</i> relevant (and the optimum choice or set of choices depends on a lot on what specifically you are doing), but if you think the value of getting the choice right is outweighed by the cost of evaluation, or if you think there is no difference, go ahead and choose randomly. It's your (and your investors', if any) money, not mine, and you should definitely do what you think is right.
The most important things in my eyes are:<p>- speed of iteration -> how quickly can you produce something that proves the value<p>- available developers -> how many people code in this language and what kind of people are they<p>- infrastructure -> depending on what you plan to do, it might be a good choice to have something that is easily deployed to a cloud service, some languages are better supported than others
For many projects it make sense to go with what you are familiar with. A side project or startup can involve a huge amount of learning and discovery unrelated to learning a language, why take on that additional burden?