"Depends on the tea" is absolutely right, but that website makes some odd claims. It reads like a content mill. Their claim that black tea should be steeped at 85 deg C is simply wrong. I don't know where they got that. Black teas are universally recognized to require the highest steeping temperatures, to the point that high-altitude brewing is a problem for many folks. The claim that green tea is best steeped at 70 deg C is similarly useless, simply because there are so many kinds of green tea. Really sweet, amino-heavy teas like a good gyokuro are definitely better done at lower temperatures. But most green teas are quite forgiving, and are commonly brewed at near boiling temperatures. Freshly boiled hot water is also often necessary for herbals, especially short-steeping acidic herbals like hibiscus and fruit.
Mate is uniformly prepared and served at around 180 deg F in my experience. Don't spill that shit either.
I've noticed a trend in recent years for tea retailers to lace their marketing with fancy instructions that treat their teas like autistic children, demanding gentle temperatures and strict timing rules. This started as a uniquely American bit of marketing wank, but it seems to be spreading recently. For a rebuttal with the credibility of an old-fashioned Englishman, here's Ginger Baker in an interview in Forbes a few years back:
> One thing that really bothers me in America is the inability of restaurants to make a good cup of tea. The instructions printed on the bag say, "Pour boiling water over the tea." How simple is that? No, they bring you an empty cup with an unopened tea bag beside it – how nice - and a pot of water that may be hot, but boiling it isn’t. So tea you have not. It’s boiling water that brings out tea’s flavor, and perhaps a dash of milk. But the brown liquid you end up with here looks like gnat’s pee, and has nothing to do with a really good cup of tea.
Even notwithstanding individual preferences, if you go to any good tea shop you're highly likely to be served a pot of freshly boiled water, which may still be well over 200 deg F by the time you pour it. A hazardous substance to be sure.