Exactly this. If you think OF bias is bad now (which it is), when Joe was at his peak, the bias was 10 times worse. If there was a Rangers or Celtic option for the national team, they were always going to be preferred. If there wasn't, then it was off to the English leagues to pick someone.
Not that guys like Sandy Jardine and Danny McGrain were bad players - but they were both right backs, and Joe was easily their equal at worst.