The mailbox flag that controls whether messages sent by a delegate get copied to the Sent Items of the original mailbox is not settable via Graph. We need to execute a PowerShell script to do this. ...
That's part of it for sure. But the real goal is to reduce onboarding barriers. We want a purely Graph-based onboarding experience for our customers. Victor is correct that for someone familiar with PowerShell, it's not a big deal. But it's still slows down the process because it's no longer just point and click.