No, in this generation, there
is evidence that raw performance has been a factor in sales and in Sony's success. Each generation is its own thing. In this one, power has mattered.
First of all,
Nielsen had a look at the data, did some surveys and showed that among PS4 buyers, the improved resolution was
the number one reason given for purchasing it, with 'faster processer' the number 4 reason. The 'meme' that PS4 was the stronger, better machine spread quickly across twitter. Anecdotally, it's what got my casual 360-owning friends to pick one up over the XB1. The survey appears to confirm that this wasn't an isolated or unusual thing.
And people were shocked at how quickly these consoles took off - the prevailing wisdom was that without any new styles of gameplay, the average console gamer wouldn't pay $400 bucks to play prettier versions of the standard multiplats like CoD / Fifa / Battlefield etc. The consensus was that, like the Wii U, there could be a good first month or two and then a rough first year as people stuck with what they knew. And the consensus was wildly wrong. The average console gamer flocked to the new machines quickly and in droves for the prettier graphics, and flocked to the PS4 in particular as it had the better visuals (and better price). And tons of PS4 purchasers moved from 360.
Not only that, people were shocked at how quickly the audience for cross-gen titles (in terms of software splits) moved to the newer consoles. This was long before there was any danger of the older consoles missing out on new games in big franchises - people just moved for the better visuals. And it certainly wasn't exclusives selling the games - just look at the sales charts at launch and for a year thereafter. Better looking versions of games we already had were the number 1 thing people were buying the machines for. If that visual impetus was what was driving their purchase, surely getting the best looking console they could would be a huge factor?
Here's a
thread where Sony claims to be shocked at the rate of PS4 sales and admits that many previous owners didn't own a PS3. (Establishing that this was, in fact, a surprise to everyone.) Shu pretends like they don't know what drove the sales, but their actions with PS4k speak louder than words - they got the benefit of being the strongest, most premium console this time around, and they want to retain that. Their actions show that they think it was an important part of their success, which is backed up by the Neilsen survey.
Honestly, how can you look at all of this and say that power doesn't matter?
It would be suicide for Nintendo to chase MS and Sony in this regard, but it would also be stupidity not to see the market as it actually is.