> It was assumed that hardware would scale to keep up with demand,
No, it was designed to stay at "one block every ten minutes" regardless of the hardware added or overall hashrate of the system. Which is why you hear a lot of people arguing over block size and block compression: you always have one block every ten minutes, how many transactions can we squeeze into that block?
The only thing that adding more hashrate does is waste more power, since the network will adjust.