The importance of having isolated environments for code testing and execution becomes quite apparent by noticing what happens when you ask a friend to run one of your Python scripts. What happens is that you provide instructions to install Python version X and dependent packages Y, X, and ask them to copy and execute the script on their machine.
In many cases, your friend will proceed and download Python for its platform as well as the dependent libraries and try to execute the script. However, it can happen (more often than not) that the script will fail because either their computer has a different operating system than yours, or the installed libraries are not the same version as the one you installed on your machine. At other times, there can be previous installations that are improperly removed and will cause hard-to-debug conflicts and a lot of frustration.
A...