I am not sure why by default syntax highlightening and line numbers are disabled, but anyway, the script editor seems too basic by today’s standard. It does not have advanced features of a dedicated IDE, and it is not even as good as an advanced text editor like VS Code. Also, when an error occurs, it is difficult to see the problem, because all Blender says is see the System console. I open and see the console, but of course, it is not as good as the error/warning panel of an IDE.
But there are lots of scripts and add-ons for Blender. Are people mostly just use Blender’s code editor? Or do they write code in a dedicated IDE and then copy&paste it into Blender’s code editor to run it? Or is there a better way?