(dare I say any?) situations where the value the two realtors bring to a transaction is really anywhere near 6% of the transaction? In the non-outlier cases (and sure, in my opinion), no way. Regular people, buying or selling regular homes, in regular neighborhoods, in the vast majority of cases - I'd put the value they bring at something more like $5,000 on the three houses I've bought or sold in the last 6 years. Nowhere near the $25,000 - $45,000 they've extracted from each of those transactions.
I despise this entrenched system but it's hard to dislodge the incumbents.