Channels vs looped memory accesses

In particular, I'm referring to Figures 3/4 from this paper: http://ieee-hpec.org/2013/index_htm_files/29-high-performance-settle-2876089.pdf

I understand this is just an illustrative example, and I think you've answered my question. That is, channels don't add much (any) functionality for simple I/O but do allow you to replicate portions of code which may have lower throughput.

Thanks!