Why is this a problem as long as bugs are separated by component? Sometimes a feature will require work on multiple platforms, and it's nice to go to one place to get a sense of overall progress. And, since the bugs/tasks are separated by component, you can get the granular view you want as well.
You could get overall progress even with separated boards.
Overall progress doesn't help us who have to open/close/comment on them.
You wouldn't use a single issue tracker for five repos, how is this different?
Regardless, they wanted to switch once they realized how cluttered things became for non-devs as well.
