Blender has a big problem with defaulting to excessive albedo (brightness) in almost every case where there is a material default. This causes significant issues. For example, this is what happens when you enable Eevee’s AO with “bounces approximation” enabled in a scene with many objects that do not have any material assigned yet:
Looks like hazy glow. It is caused by excessive, unrealistic bright color almost no materials in the real world have, except a few like fresh alpine snow.
The color of objects in Eevee viewport without any material assigned is hardcoded to such color. Furthermore, any newly created PBR materials have separate color for workbench shading, instead of using Base Color from PBR shader:
This color also defaults to extremely high 0.906 value. And so does the Base Color value itself in the PBR shader.
The extremely high default albedo values have negative quality implications when it comes to both Eevee and Cycles, and also severe performance implications when it comes to Cycles performance, as path tracers in general tend to slow down to crawl when one uses unrealistically high albedo values. It tends to ruin image realism on top of that, killing most of the realistic contact shadows.
Lastly, it has also negative impact on newbies using Blender. Since newbies usually tend to trust the defaults, expecting them to be set up by developers whom should know what they are doing, this could instill wrong practices and habits within them, not realizing that default Base Color in PBR material for example defaults to something that is much brighter than average newly painted interior white wall.
So it’s time for Blender to finally get default color values right, especially when some of them can’t be edited, even by adjusting default startup file. We should encourage people by having them getting good results out of the box. I suggest color value of 0.5 for all the newly created materials in Base Color, Viewport Display color and objects which have no material assigned yet.