> doctors are rather good at providing care across corporate boundaries

I’ve found that to not be universally true. I say that as someone with eight different health systems in MyChart and who has been treated by two additional hospitals who don’t use MyChart in the past year.

Some systems are very competent about sharing across borders and good at it. I’m lucky my primary hospital is one of those. Others are god awful at it and take multiple calls to get them to even fax records.