I get what you are saying but I don't agree with all of it. I should really dig up the article to make sure I am stating their words properly but they make it clear that the higher voltage levels are for connection between devices using a professional level and not the consumer market. Then they go on to say why which is because the lower voltages can't do the signal down to those amazingly low levels of noise. Benchmark really aren't trying to upsell themselves as a marketing ploy. I totally trust that they are just providing information to explain their decisions, which is fine with me if you think it is still snake oil. A difference of opinions is a healthy thing as long as you don't ignore science. This stuff is getting so good now, only the priciest and unobtainable (to most) testing equipment can even back it up with numbers.Benchmark just want bigger numbers to advertise, so, like plenty before them, they want to play with output levels to push their signal further away from the relatively fixed (on SOTA gear) residual noise floor.
Amplifier makers have also realized they can also tout bigger numbers if they dispense with, or at least reduce the gain of (and the consequent noise) their front end (VA) stage.
It's just a case of playing hot-potato with the consumer stuck in the middle.
2V was 13 times and 22dB above the standard for consumer gear at the time. It was a marketing number driven figure and was changed at the absolute last second to get better numbers.
Now we seem to have few real preamplifiers out there, so the 150mV sensitivity for full rated output is disappearing and the inroads of the 'pro' level and XLRs are creeping into the home. It's funny, for many decades, the ubiquitous Cannon XLR was seen as defining gear made for the sound reinforcement scene and not of audiophile quality. Just the presence of an XLR immediately turned audiophiles off. In the 90s, they started sticking them on anything and everything- mostly with a degraded performance when compared to the RCAs. Now audiophiles can't bring themselves to lust after products without the silly things. Swings and roundabouts.
So where will it end and, what's next? Until we have a D/A converter that can drive +/-70V into a separate power stage, the games will continue. And we'll need a new connector of course. A safety retractable multipin derivation of the XLR because you don't want a fatal shock from your D/A converter do you?
I agree with you that good hardware connectors and the like do end up getting abused by the general market with their "See, we used that stuff too so our stuff must be the best too!". I look for things with XLR not to feel it will be better sounding, but because it is a more robust connector with better contact resistance, if kept clean. It's all about paying more attention and looking for reviews of things before jumping in. That's why I am here at this site, for sure.
I also get your exaggeration with the 70V DAC and the truth is that everything has limits. The slew rate on such a voltage would be impractical but someday that might be the best way to go. We've got 120/240V plugs laying all over the place with holes in the wall to get access to it. People who wear electrostatics put 500+ volts into their headphones. You gotta take that risk to get the best sound. Ha ha.