[G6Tanuki]

IMHO inless a "S-meter" is properly calibrated [which generally means it's fitted to a measuring/test-set not a general-purpose radio-receiver, and you're feeding it a signal from a fixed-impedance non-reactive source...] the only real use for such a meter is for things like peaking-up an ATU or optimising the direction-of-point of a beam antenna.

[I once had to design a precision logarithmic detector with a 60dB operating range. Not an easy task, and it cost quite a bit more than your average amateur transceiver. So what hope for a S-meter in such a transceiver where the designer probably only had a couple of dollars-per-feature to spend?]