(Telco employee here who deals with UPS/Electrical issues frequently)
Everyone is reading way too much into this. What we have here is a classic case of voltage sag:
https://en.wikipedia.org/wiki/Voltage_sag
What is most likely happening is the power delivery system either the battery or the the corresponding coils/fets are insufficient to maintain 100% load from the CPU, full stop. This is a hardware issue that existed from day one and is unfixable. The issue with the batteries degrading is a red herring and is only a symptom of the true problem. Apple knew this was an issue and could not fix it and rather than risk a thermal runaway from the battery aka Galaxy Note 7 they put this "patch" in place instead of doing a full out recall. (which is what should have happened).
When we configure our power plants we always use N+1 or have at least double what is required to run our plant. Apple clearly does not and dangerously overextended their power delivery. Whether it is intentional or not from the design originally remains to be seen.
They are ****ed and should be hit with the highest penalty possible up to and including replacing everyone's handsets with a different one. This is not some "oh golly gee" but an intentional "they won't notice because they're stupid" sort of thing.