Even the SNES didn't come close. Wasn't until the Sega Saturn era that we saw something that could outperform it.
One major reason is sprites: Amiga can display 8 4-color sprites, or 4 16-color sprites, and the colors are shared with the bitplanes.
SNES can display 128 16-color sprites, and the sprites get 8 palettes all to themselves.
This leads to much more colorful-looking visuals on SNES. Since Amiga is all bitplanes, enabling more colors and higher resolution results in a massive performance hit. Most game entities would need to be blit on top of the background, and then the background "restored" every frame that entity moves. SNES' native support for multiple tile layers and good sprites means that the CPU can do a lot less work to achieve a lot more.
Amiga can do some very cool stuff that SNES can't, especially with the blitter, but SNES is much more practical and powerful for video games.
Per scanline. However, you can multiplex them with copper to your hearts content.
"SNES can display 128 16-color sprites, and the sprites get 8 palettes all to themselves."
32 per scanline, but then almost all of those sprites would need to be 8x8. Just 17 of 16 pixels wide sprites.
BTW. On AGA (Amiga 1200, 4000 and CD32) each sprite could be 32 or 64 pixels wide but I don't think that feature was used much by games.
So was the Amigas chipset - it was originally designed as a games console and pivoted to a home computer when the games console market tanked in the early 80s.
Assuming you are not rewriting the palette scanline-by-scanline...
Amiga is stuck with 16 colors for the whole bitmap screen unless extra-halfbrite mode is used, then it goes up to 32 colors (extra colors must be half as bright as the base colors). Using the hardware sprites (3 colors + transparent) can add up to 12 more colors.
Meanwhile on the SNES, the most-used video mode has two background layers with 15-color tiles (plus transparent), and one background layer with 3-color tiles (plus transparent). 8 different palettes can be selected, for 128 colors.
Then there are sprites too, lots of sprites can be on the screen at once. 15-colors (plus transparent) for a sprite, and 8 different palettes can be selected.
Then afterwards, color math can be applied, you can make graphics use additive blending (light effects), subtractive blending (darkness effects), or 50% transparent blending.
The copper was also used to multiplex sprites, so again the limitation is per scanline.
And assuming things wouldn't be changed per scanline is assuming a shoddy job - very few games on the Amiga would not make at least some use of the copper to extend the number of sprites or number of colours on screen.
Though the Amiga does allow changing the positioning of the screen over a larger bitmap, so e.g. panning the levels without much/any copying might have been an option? Doesn't require the copper, though.
A few of the more sophisticated efforts could be argued to be technically superior to anything on the SNES; consider Shadow of the Beast 3 or Lionheart.