This is simply the mindset of discount airlines. If your battery is dead when you arrive at check-in that's too bad for you. It's in the terms and conditions.
If the server is flaky then boarding will be delayed for everyone and it'll be a whole crapshow but if their overall cost is lower than it would have been with printed boarding passes, fine.
Usually they'll happily help you out with a "late boarding pass printing fee" on the order of a hundred €/$, though.
If this really is a total refusal to do even that, I'd be slightly surprised, but I'm sure their business developers have done the analysis and it makes some sense to them.
If the server is flaky then boarding will be delayed for everyone and it'll be a whole crapshow but if their overall cost is lower than it would have been with printed boarding passes, fine.