I’ve worked with some pretty rotten software, but management software is easily the most user unfriendly, so my vote goes to HPSM.
Maybe you have heard about a software called Ragtime. It‘s basically a combination of Word and Excel. However, there‘s no option to export any files that can be edited with any other office application, and you can‘t open .xls/.odf etc files with it. Oh, and the best part about it: You can always only undo one action.
Several decades ago, it must have been as good as other comparable products on Mac OS. And when there‘s no compatibility, the switch isn‘t that easy. You basically have to build your templates from scratch.
That being said, we have decided to switch to MS Office, but my boss will probably use Ragtime until retirement.