No. Group C was done in by Max Mosley and Bernie Ecclestone because it was threatening Formula One. The costs became prohibitive not because of competition betw

No. Group C was done in by Max Mosley and Bernie Ecclestone because it was threatening Formula One. The costs became prohibitive not because of competition between teams, but because of new rules that favoured the manufacturers by making F1 engines (which were very expensive) all but required if you wanted to stay competitive. And after the privateer teams were gone, there was no real reason for the bigger teams to compete with each other in Group C when they could do so in F1 with the same engines: an outcome which very nicely lined Bernie's pockets.