Reading the explanation, the idea in реки is that the information about the "softening" is contained in the е that follows. So it's replaces szcz-like rules wit

Reading the explanation, the idea in реки is that the information about the "softening" is contained in the е that follows. So it's replaces szcz-like rules with other rules, which admittedly follow the logic of some existing rules in some languages, but which makes the result still less directly "phonological" than some other approaches could be. At least the author admits it's "primarily a thought experiment". Interesting anyway.