I don't see the problem with pausing the game - I turn the computer off every night, I watch Iplayer I answer email I pause the game all the time.
That's different than what people are describing in this thread, though, is it not?
No, it's not gamebreaking to pause the game, when I feel like taking a break, answer the door or order pizza, but it is immersion breaking when I'm forced to pause the game in ordert to not be overrun with messages about babies growing up, being born or animals having died, currently almost starving, having escaped their habitat or whatnot.
I played a lot of Prison Architect and yes, there were situations where you were busy planning a new cell block while your inmates suddenly became busy killing a snitch you did not know you had. But overall it is easily possible to deal with situations as the game still progresses, research is happening and things are getting built. I normally pause the game if I have to do something off screen (e.g. answer a chat message or email, to use your examples again.)
Planet Zoo is different, though. Honestly, I just feel like the balancing is off in this game. It never was an issue in PlanCo that time flies and visitors are in the park at all hours of the day. Yes, your rides were slowly turning old and weren't as hip and cool anymore, but I was happily building things while my guests were enjoying the park. Planet Zoo, with the animals having an expiration date, growing up and mating with their siblings if you're not careful, is a whole different beast, though. I'm not pausing the game because I do something outside the game I am pausing while doing stuff IN the game because otherwise the Zoo would get out of hand in no time. It just feels off and more stressful than I care for.
Now, obviously. Not EVERYONE feels, that it is too fast. But there are two faster speeds (2x and 5x normal speed, I believe?) So if they slow it down, you can still play at a faster pace. But all those, who feel, it is too fast as it is, have no option to slow things down.