The same is also true, say about AirDrop, if apple makes it "Open" and they have to make a breaking change for security or whatever reason, they can't feasibly even make an update available for non-apple devices let alone enforce it.
Now "Apple" has broken your non-apple device and along with it their reputation.
Open is good, but the cost is non-zero.
This argument is silly. You could use this line of reasoning to justify why all computers should use the same OS from the same vendor. Of course then you'd have a monoculture where implementation bugs that cause vulnerabilities are universally exploitable, instead of only exploitable on machines running that vendor's software.
Far from it, actually.
If a part of your user base uses another service, you’ll inevitably have to add workarounds specifically to cater to users for that service. It’s just a fact of life when multiple groups have to implement a spec. If you aren’t willing to add workarounds, users will think your software is broken when they should be blaming someone else.
For example, Firefox maintains a few workarounds for websites that ship in the browser. They aren’t the web developers responsible for the sites but someone has to make it work.
Interoperability is not free.