Thanks for the request. Currently there is a way to set this property through powershell for groups, but it only works for users in OWA. We have this in our plans for Outlook desktop as well and will be working on it.
An error occurred while saving the commentGreg Baughman commented
This is certainly an issue... o365 calendar is the only one that works on mobile (sharepoint / etc. doesn't) but people can't add their own items without being a calendar owner!
This really needs to be resolved...
In both Outlook 2016 and on the web. Permissions just "Greyed out". What happened to "Contributor" permissions????