It&#x27;s the old diversity vs. centralization&#x2F;standardization argument.<p>Too many programming languages leads to too much fragmentation, not enough programmers well-versed in the languages, etc.  Most times, we pick a language today based not on how optimized the language is for the problem, but on the availability of programmers who know how to use it.  Haskell might be great, but if you&#x27;re a business trying to build something, you&#x27;ll have a much easier time hiring experienced C++ programmers.  However, different languages have different strengths and weaknesses and applicability to certain problems, so you don&#x27;t want to just standardize on one either.  You probably wouldn&#x27;t use Haskell on a project that is a good fit for C and needs low-level access to hardware.<p>It&#x27;s not much different with version control, except that fundamentally all such systems aim to solve the exact same problem: managing and keeping track of source-code changes in a project.  They go about it differently (distributed vs. non-distributed is a big factor), and offer different features, but they all want to do the exact same thing.  And here again, programmer familiarity is an important factor.  Working with git is not even remotely like working with ClearCase, for example.  So people tend to gravitate towards popular choices, which was SVN before, and now has become git.  So if you pick Hg for your project, you&#x27;re going to probably have to spend more time getting contributors up to speed on it than if you picked something more popular like git.<p>One big factor in these debates is: how easy is it to change from one to another?  Another is: how easy is it for individuals to pick their favorite and use that regardless of what others use?  For programming languages and version control, you can&#x27;t easily change between them, and everyone needs to be using the same one on a particular project (unless you do something where one part is written in one language and linked to another part in a different language through bindings, but this doesn&#x27;t apply to version control).  For editors, this isn&#x27;t the case usually: any programmer can use whatever they want for the most part, and it has no effect on what others use.<p>As for your other examples, build tools are the same as version control: everyone has to use the same one on a project.  You can&#x27;t have one person build with make&#x2F;autotools and another with scons and another with CMake.  This doesn&#x27;t mean you can&#x27;t change it later if there&#x27;s a compelling reason, but there&#x27;s inertia to overcome once a project is built a certain way.  ASCII did win, that should be obvious.  Even Unicode is largely based on ASCII with utf-8.