Is there a way to pass multiple artist IDs and get all of their albums, thus reducing API calls?

Not currently, no. For the moment you'll have to rethink your user interface - do you really need all that data at once, or could it be lazy-loaded? If it's a data processing tool which runs on the command line or as part of a website, can you tell your users that it will take some time to fetch everything?

Feel free to expand on your use case and maybe we can figure out a workaround until a "get albums for several artists" API endpoint exists.

Just popping into this thread to mention that I also would like this endpoint.