I don't think Renault stood still on the power front, they most probably did improve but not as much as the other two. Nugnes says that Merc also had some issues with overheating of the hybrid part of the PU, and we know about their clipping issues. I think if Mercedes could stretch their legs they'd be clearly ahead of Honda, and Honda a not too big distance away from Renault
I think this confusion is a consequence of the rule change last year. If all the PU manufacturers could use full power in qualifying it would make it easier to paint the picture (Albano mentions this in the article), but with the single mapping rule everything becomes more blurry because there's more variables