I suppose it technically can, but this assertion makes me ask: why haven't we seen this actually happen? I mean yes, we got consistency -- but at a pretty serious cost in terms of usability.
These findings also confirm that flat or flat-ish designs can work better in certain conditions than others. As we saw in this experiment, the potential negative consequences of weak signifiers are diminished when the site has a low information density, traditional or consistent layout, and places important interactive elements where they stand out from surrounding elements.
https://www.nngroup.com/articles/flat-ui-less-attention-caus...
And this is what has happened. All over the modern web and applications there is a low information density which means I need to carry more context around as I browse through things.
The article goes into it more in depth but flat design is bad in almost all regards apart from one: anybody can be a designer now.. the barriers to entry are that much lowered.