This is almost entirely untrue. AFAIK the only studies showing that breakfast is "the most important meal of the day" are those sponsored by Kelloggs.
The slight grain of truth is that people tend to be either owls or larks. If you feel hungry first thing in the morning, by all means, eat breakfast. If you don't, there is zero harm whatsoever in skipping it. The idea that doing so slows down your metabolism has been thoroughly debunked. In fact, eating breakfast tends to be correlated with weight gain, if anything.
https://blogs.bmj.com/bmj/2019/01/30...al-of-the-day/
OTOH there is some evidence emerging that meal timing (not necessarily breakfast) is important, but this seems to be more to do with restricting the eating window (i.e., intermittent fasting) to give the digestive system more rest & recovery time. Contrast that with eating constantly throughout the waking hours, which is only been a viable thing for humans relatively recently and not something we evolved to do. We're not cows.
One thing that probably is true is that, if you are skipping breakfast but instead, eating late at night, just before going to bed, that is almost certainly a bad thing. But it's not the skipping breakfast part of that which is the bad part. Those two things aren't necessarily connected, except that if you do that you probably won't feel hungry in the morning.