Ok, this may be controversial, but I will yes and no.
Yes, if you want to max out on a specific hardness, it needs special HT. Special, as in more difficult than carbon steel.
However, I HT it like normal carbon steel, but a bit hotter. And I get consistent 59.5 HRC as verified by Mike Blue, with a very fine grain structure.
So I say no, if 59.5 is high enough for you.

And as you say, it can be bought in 6.5 mm which makes it ideal for making razors.