Yeah, I think people automatically assume that others are trying to double-up bass to get more power and miss the point. Using this an option to compliment the natural 3dB downpoint of bass from bookshelf speakers is beneficial if you're trying to bypass the DACOne thing that thread seemed to miss in all the ranting from those not wanting the behaviour is that the behaviour is optional.
There's a "Subwoofer" setting in "Surround Parameters" that controls subwoofer output for Stereo and Direct modes when LFE+Main is engaged.
The "Subwoofer" setting is on by default, so the behaviour happens if you select LFE+Main (which is not on by default), unless you find that setting and turn it off. I believe it's only visible when actually in that mode, like other Surround Parameters that only appear when relevant.
And at least on some models, it actually is a fixed-frequency analogue 80Hz LPF, not going through the DSP, at least if using a direct analogue source.
(I'm talking from Denon experience here - I expect Marantzes are similar).