The research into dark mode’s effects is far from conclusive. But anecdotally, some people claim that using dark mode does benefit them.
Studies on whether dark mode and other blue light filtering solutions work to mitigate blue light exposure are inconclusive. However, it seems dark mode is more likely to affect sleep rhythm than eye strain.
You made a categorical claim that is not substantiated. In fact, you’re even ignoring evidence to the contrary solely because it’s anecdotal.
As the idiom goes, absence of evidence is not evidence of absence.
Just because the evidence is not to your liking it doesn’t mean there is not any evidence.