Emergent self-organizing maps from tetramer frequencies (binning metagenomic contigs)

Question

[5heikki]

I've been rather successful in assembling bacterial genomes from relatively complex metagenome assemblies following this protocol. I'm just wondering, how come it works so well? How come we can derive from tetramer frequencies what sequences come from what genomes? What's the biological basis of this? Wouldn't we expect that tetramer frequencies were completely different between e.g. rRNAs and protein-coding genes?