I agree. Every web design tutorial I've ever seen since the mid 1990s warns against implementing a white background. White on a screen is way too glaring for the human eye.
The layout shouldn't be changed so often. People navigate a virtual spaces like a website the same way they navigate an IRL space: remembering visual clues around them. When the look of a website keeps changing all the time it's super confusing trying to navigate a site, even if it's a site they already know and everything is technically still in the same place. It's like they have to find their way around anew every time.
For me myself, I've already indicated that I don't want a light background and that I will select a dark background on any page where that's an option, so I shouldn't have to pick a new dark background every time. It's just unnecessary.