Yes, but this does not conflict with the Shannon-Hartley theorem, which gives the upper limit of channel capacity for a combination of bandwidth and SNR.
The actual number of bits transmitted and received correctly cannot exceed that limit, not even for a super-human on magic mushrooms.
However, if the message contains redundancy (e.g. repeating the RST or callsign), the net amount of information that is being transmitted for a successful QSO is lower, hence the channel capacity required is lower. And slower CW requires a lower sampling frequency. This is the theory that explains why we can understand 12 WPM with RST given 3 times from much weaker signals.
Redundancy can also be in the transmitted text; if the characters are not completely random, but from a set of Q-codes, and there are some conventions in the structure of a QSO, the actual number of bits of this message is lower than that of the raw sequence of characters.
This is called entropy encoding and is the same mechanism that you are using when compressing a text file prior to sending it over the Internet.
Second, if the receiver knows part of the message (which may be just the likelihoods of some events, e.g. that a certain CEPT prefix is more likely than another, or the next word if you know the previous one), then the actual number of bits required to be transmitted and hence the net bit rate is again lower (to be precise, this is just the other side of the entropy of the transmitted information).
This is the theory behind the observation that we can read CW faster in QSOs with common Q-codes as compared to random strings of characters when training CW.
So while you are right that the actual power ratio is dependent on additional aspects, the power ratio is not outside the reach of scientific discovery, at least as an approximation.
It is not “unknowable spiritual glibbery that only gifted souls can conceive under the influence of strong homeopathic sugar drops” .
Please be assured that I am not at all implying that you were claiming or even hinting at such a perspective. I just want to carry the torch of the Age of Enlightenment as high and as far as I can.