I don’t understand it either. Know the status of your firearm and if one doesn’t than one should check. There shouldn’t be live ammo around when cleaning or working on a firearm anyways.
I personally do not have an issue with having to pull the trigger to remove a slide. Gun safety is first and everyone should be verifying that any firearm they are cleaning or working on is unloaded.
Then again some people refuse to carry striker fired pistols that do not have a manual safety nor trust the trigger safety shoe or firing pin safety plunger. Then there are others that won't carry a 1911 cocked and locked even though there are two safeties that have to be manipulated before it will fire.
To each their own, use/carry what you are comfortable with. 1911's cocked and locked along with striker fired pistols without a manual safety do not bother me one bit.