No way, dark mode is great. Combine it with an internet browser that has a night mode (Samsung's fork of Chrome) and the phones are significantly more pleasant to use at night.
Dark mode is only great if absolutely every single website and app you use support it, and you are never shown bright images ever, because then your eyes explode. This is, it's useless.
That's a fallacious argument. Imperfect solutions can still be superior to the unmitigated problem, and they are in this case. You're essentially arguing that unless the solution is perfect, they shouldn't even try, and I'd point out you haven't justified or even tried to justify that black or white point of view.
In this case, yes. I think it's better to use light apps at a low brightness level than to use dark apps that might or might not blast a white screen at you. I think that flash of light is terrible for your eyesight, much worse than constant light apps.
I'm inclined to agree with you that sustained periods of darkness that include rapid change of light level may be less healthy for the eyes than consistent levels of overall brighter display with such shocks, but I'd like to see some research to back it up.
This is a prerequisite for that. You're not gonna manually turn on dark mode in every single app for much longer, your OS will support it as a setting and third-party apps (including browsers) will read that setting and adjust accordingly.