Some cross-platform tools were built assuming that the environment in which they run behaves like Linux. For example, some tools assume that they are able to access very long file paths or that specific files/folders exist. This often causes problems on Windows which often behaves differently from Linux.
Many languages like Ruby and Node.js are often ported to, and run great, on Windows. However, not all of the Ruby Gem or node/NPM library owners port their libraries to support Windows, and many have Linux-specific dependencies. This can often result in systems built using such tools and libraries suffering from build and sometimes runtime errors or unwanted behaviors on Windows.
These are just some of issues that caused many people to ask Microsoft to improve Windows’ command-line tools and what drove us to partner with Canonical to enable native Bash and Linux command-line tools to run on Windows.