You make a good point. At the risk of sounding like a bitter Dundee fan, I think United's title success in 83 owed a little to Aberdeen stretching themselves in Europe. Jim McLean was an outstanding coach though and I wish we gave him the job at Dens he desperately wanted in the 70s.
The New Firm wasn't a myth because I don't think the idea of the New Firm was that they totally dominated Scottish football. It was that they challenged. As much as I hated being second best in the city part of me does miss being a kid when Rangers and Celtic were regularly beaten. The season before Murray arrived and brought Souness in and started dumping all the shit that is now hitting the fan, Dundee went to the last day with Rangers in the battle for a European spot. That's quarter of a century ago and a lot of medals, trophies and European trips that went to the wrong team. That's why this "treat them gently" shite really fucks me off.