The online arms of B&M stores being out of stock is a meaningless fact.
Fact is, I could walk into nearly any Gamestop, Target, Walmart, or Best Buy in my area and pick up a PS4. The "supply constrained" thing doesn't hold water if you're just looking at online sources.
Otherwise, you could say the Xbone Controller is also "supply constrained", as Amazon has been sold out for a few days now. I'm guessing there are hundreds to be found in local B&M stores, however.
I honestly don't know why this topic is so important to people. Sure, there is a decent continued demand for the PS4. But since we don't know how many they're actually shipping here compared to the rest of the world, it's impossible to measure true demand. Xbones clearly have much better demand than we thought as well, given NPDs, it just means Microsoft did a better job with supply.
Supply constrained means there's not enough units to fill the channel. Since there are clearly not enough units to fill the channel (or else the online units would be selling them), it's supply constrained. Your retailer anecdotes are the fact that's meaningless.
If the xbone controller is out of stock then it's supply constrained too.