I don't think it's fair to say they were completely stubborn about it. Porsche have used rear (e.g. 911), mid (e.g. 959, 917, 956) and front (e.g. 928) engine

I don't think it's fair to say they were completely stubborn about it. Porsche have used rear (e.g. 911), mid (e.g. 959, 917, 956) and front (e.g. 928) engine layouts over time. The 911 is iconic though and customers like its design so they've persevered with it.