Implemented the same way as STL or GPencil SVG importers: loop over the input files, import one by one. Has been requested by the community for quite a long time (e.g. https://blender.community/c/rightclickselect/Jhbbbc/), as well as 3rd party addons to implement just this (https://github.com/p2or/blender-batch-import-wavefront-obj).