I'd half agree with that... temps on my ref Vega on full load aren't great, but at the same time the noise is reasonable and other than the Destiny 2 crash (driver update fixed) I haven't had any major issues. I have my minimum fan speed set to 1600 and max to twice that at 3200. Would I prefer slightly lower temps? Sure, but for what it's worth I don't think the cooler is inadequate for the 64, per say.
As a side note I was playing Deus Ex earlier and some of the world geometry started freaking out but the game continued to play without a hitch; no artifacts. I did notice that title using very close to the maximum amount of video memory also.