Eases the job of selecting a bunch of nodes of the specifed type. Useful to select those type of nodes that are not in the viewport and thus you have to dig in some other panel to select them, when you have scenes populated with hundreds of objects for instance or you want to select file nodes, shaders, utility nodes, whatever...
It also allows you to have a current selection and filter it so only a nodes of a specified type remain selected. You can refine even more the resulting selection using the string filter to select only the nodes with certain name within the specified nodeType.
Maybe is not an tool to use on a daily basis but I have found it useful and it has been made due to a need, so it may be useful to you too. Who knows?
Any feedback appreciated. Thanks