I wish i could know that, or better say Steinberg knows 
since the hanging on exit is old issue and many users encounter with. Luckily isn’t deal breaker since hanging is occur only on project/Cubase closing, its hassle when you open many sessions through out the day though… The same question can be applied how does the Reaper never hangs on same machine/system?
My point would be that Steinberg doesn’t testing enough, and quality check control is not on best level as this 10.5 confirms with all hotfixes and topic about slow on Mojave which has 22pages so far. For my particular case 10.5 wasn’t usable till February 3 (82 days from the release)
Wondering are they have enough beta testers…