Asking Too Much
It's good to trust others but not to do so is much better.
I noticed recently that I could now link my personal calendar into my work Outlook account. It would likely remove some degree of duplication, probably make planning easier and would definitely be a much more viable option that doing things the other way around.
Without any explanaitions, here’s what Microsoft deem necessary for them to be able to read my calendars:

Needless to say, I immediatley hit the cancel button. This is a massive overreach in terms of permissions as far as I am concerned. In order to view entries in my personal calendar, I need to grant wide-ranging capabilities to my work account – such as the ability to delete my emails or view my date of birth? Why are these a requirement?
I have high hopes for Tim Berners Lee’s Solid project. I’m really holding out for a solution that will let me control my own data and make decisions on a case by case basis for which applications can see what information and for how long that access should be valid.
I’m not holding my breath.