I couldn't see that being the case. In painting, it is common to have smaller, tighter brush strokes at the focal point, and larger, broader ones away from it
The great thing about pixel art is that it's not painting, though! I always get paranoid with real media art because I'm not manipulating the 'atom' of my artform, there's always a theoretically smaller one hair brush I could be using, I never know when I'm done and I never know if the broad strokes stand for themselves or what. Pixel art, for those that love it for what it is, is a remedy to that feeling, because you're always manipulating on the atom-level and trying to get your pixel clusters to be elegant and work together as best they can. This is why it makes zero sense for me to put a different resolution on a different resolution. Different grid means that the eye on the bird just made all the pixel clusters 'beneath it' be inelegant and chunky.
And what Jad said about the pixel tying all things together is very evident in almost all my favourite 8-bit and 16-bit games. I had to develop an outside language to video-game talk to be able to express why pixel art doesn't deal well with mixed resolutions, but it applies to game art too.
The strange thing is that there IS historical precident for mixed resolutions. On the c64 you could have a high res background and a multicolor widepixel sprite on top (or the reverse). On the Atari, sprites were quadriplewide I think for machine reasons I never understood. Scaling effects, Pokemon, as you mentioned, there's lots.
But my eyes and heart will never accept it as a strength in pixel art.