Definitely agree with this. Over the past five or so years I have adopted the following approach that ensures have control over 95% of the interruptions:
- I have "silence unknown callers" enabled in iOS
- Focus mode is on 100% of the time.
- I disable notifications for all apps except for Reminders (interruptions I have configured) and the Phone app (calls from people in my contact list).
To your last point, the people I am actually interested in talking to only call if something is too important/time sensitive to do via text, so this works well. Any other callers will leave a voicemail if it's actually important.