I've no idea about the blur.
June 17th is the new version. One more month.
From the help file:
The Gaussian Blur effect softens the image and eliminates noise. Adobe Media Encoder applies the Gaussian Blur effect as a pre-encoding step. This step minimizes the noise that the encoder would otherwise have to encode. It results in quicker encoding and smaller output file sizes. Select the Output tab to preview the results of this effect.
My guess is that noisy video is usually fixed in the timeline, but maybe not?
I used the Gaussian Blur just yesterday to take the edge off a few supers for an encode. It comes in handy but I know what grisdelaluxe means - most other encoding programs I've come across (actually, all of them) offer the user a whole suite of filters to tweak the exports. I really notice the lack of Sharpen, Gamma, Contrast, and Saturation filters for example, and will often default back to Episode or TMPEnc for certain files if I know I'll need the filter functionality. Often these tweaks aren't appropriate to use in the timeline for the full HD renders but do come into play when exporting smaller frame sizes or dealing with QT gamma shifts.