They have the most potential growth though which is where it does make sense. Hearts in particular have a good potential support being an Edinburgh based club so if they were successful more often their support would grow easily
you could argue Dundee United Dundee St Mirren and Partick Thistle for similar reasons - teams already at the top you can't really grow whereas these clubs outside the traditional ones have much more potent in my opinion. Certainly the ones with big catchment areas around them