The reason is to avoid npm/node. And that's absolutely right -- I'm a backend engineer, and I've done Vue projects with npm, and npm is fantastic -- the quality and care that has gone into it is obvious; even the screen output is beautiful (compared e.g. to the mess that JVM developers make, who think of a shell as some weird thing that someone might need to use if their IDE is broken).
However. For the OP's question, a toolset for quick and easy frontend development for a backend engineer who doesn't spend much time doing front end, avoiding npm is definitely the way forwards. It introduces a HUGE amount of complexity to a project who's aim was simply: produce some HTML and CSS with the necessary javascript to make the UI work. If your typescript compiler or Vue/React transpiler or bundler isn't working quite right, it is completely non-obvious to a backend engineer who isn't familiar with npm what to change in package.json to fix it, or even how to go about debugging it.
However. For the OP's question, a toolset for quick and easy frontend development for a backend engineer who doesn't spend much time doing front end, avoiding npm is definitely the way forwards. It introduces a HUGE amount of complexity to a project who's aim was simply: produce some HTML and CSS with the necessary javascript to make the UI work. If your typescript compiler or Vue/React transpiler or bundler isn't working quite right, it is completely non-obvious to a backend engineer who isn't familiar with npm what to change in package.json to fix it, or even how to go about debugging it.