It is actually. I posted the proof a little earlier.
Ok, but has PCIe 4.0 SSDs been available forever? No.
And how much do they cost for the same speed as the one found in the PS5?
How was it viable to put one such drive in older console, as you said they should have, when the expected selling price of these consoles is supposed to be around 400 bucks?
A quick look at the store and you have to pay around 200$ to find something comparable to what is found in the PS5.
Now, if you want to play on words, the hardware developed to support the SSD is a big deal. The use of SSDs in console will greatly affect how games are designed, as it removes one heck of a bottle neck that has been present ever since they moved from cartridges to discs.