Two Main Reasons
Developer Working on Multiple Projects
In a real-life scenario, it is common to see a frontend developer working on multiple projects in a day. So, let’s imagine you are working on three different projects and you got a brand new laptop. Below are the steps that I presume you would do:
1. Clone repositories
2. Install dependencies (node_modules)
Then try to run the project and you get the error that node version that you are using for one project is not supported for another project. So what do you do in this case? Either upgrade or downgrade the version or have two Virtual Machines (VM) running two different versions of node. But running a gigantic VM will take a hit on your hardware — unless you are using the cloud resources.
One Server with Multiple Projects
This scenario is similar to the previous one but with a small difference. Here, the impact is on deployment and not development. As a developer, you might not care how your application would be deployed and whereas it is a worry for your DevOps team and not yours.
Generally, small organizations have on-premise servers to serve all the projects and on average we assume there must be at least 15–20 projects. So chances of having conflicts in different versions of dependencies — be it nodejs or anything else — would be more here when compared to the previous one. Consider you are in hurry to deploy your application to showcase the demo to your client and stumble upon this issue of different versions, what would you do?
1. Will you uninstall the existing version? Of course not. You cannot do that else rest of the applications will break.
2. Will you set up a new server to host all apps using the same version of node on one server? But it is a costlier option.