The ubiquitous five-way binding posts are hard pressed to cope with the mechanical stress imposed by the massive cables folks use. 12AWG is about as far as five-way will comfortably handle.
Speakon connectors address five-way's shortcomings but are still largely absent from the audiophile world. There are signs this is changing though, for instance Linkwitz uses Speakons in their LX521 flagships. Benchmark does too.
If Furutech, WBT et al start making $500 Speakon connectors, they may yet become the audiophile standard.