A bot is set of tasks so inherently you will export all the tasks when exporting a bot. It is also possible to choose which tasks you want to export in the bot.
A Dialog task is individual task within a bot- so if we do not want to export multiple tasks (bot) and want only one- the feature of exporting Dialog task was provided. So when the question is Bulk export/import but without the bot - it is outside the purpose or logic of the features designed. There “was” a feature of dialog task only export which is deprecated because it did not take care of the integrity constraints of reusable components etc. Read this post to know more details on deprecation and work-arounds
So to answer the question with bot export you can achieve multiple task export or import. However, without bot export/import this cannot be achieved.
There is Bot export /import which allows for multiple dialog tasks to be exported or imported at the same time. You also will have an option to select which dialog task you want to export when performing a Bot export task.