Yeah, this is sad. This is the one and only PSU calculator I use and have recommended dozens, probably hundreds of times - for nearly 20 years. No other is as flexible with its options, or as conservative in its estimates. None want to suggest an under-powered supply so they all pad the results. But due to this one's flexibility, and on-staff researchers keeping their databases current, its padding is the most conservative and estimated minimum PSU requirements the most accurate.
What will be interesting is that there are some PSU makers that use a licensed, limited version of the Extreme OuterVision PSU Calculator.
Enermax uses it, for example. I am curious what will happen to it.
The be quiet! calculator is okay but is very limited in comparison. Plus, they want to sell us one of their PSUs and top of their recommendations list is always their top of the line, most expensive, monster supplies. You have to scroll down to get to a more realistic match.
Graphics card makers and their recommendations are the least accurate, IMO. They almost always recommend a supply way WAY bigger than what we actually need. Some don't list the associated hardware (CPU, drives, RAM, etc.) used in their estimates. So typically we have no way of knowing what is realistic for our hardware.

At least we know going
too big doesn't really hurt anything, except our budgets.
There is talk over at TPU to take over hosting the calculator, but sadly, Axel, the primary researcher (and I assume owner), has not responded to any attempt to contact him.

I have had several dealings with him in the past and he always was quick to reply, typically within hours - so I fear perhaps health issues have fallen upon him. That's strictly an unfounded WAG, however.
I will certainly miss this valuable tool. It has been great at showing the less experienced they don't need a 850W supply
with their specific hardware when a quality 550W will easily do, with plenty of room to spare.