At least, that is what public health messaging has told us for however many years, and who are we to argue? Being hungry usually puts people in a bad mood, and ideally, we want to start things off on a positive note, so we've got to get ourselves some of those crucial nutrients before we do much else. Even if what we have for breakfast is not exactly the pinnacle of healthy, we can argue that making time for it is basically an act of self-care. We're going to need that energy.
While it might be the meal that people are most likely to keep the same a lot of the time, that isn't to say that breakfast can't come with a lot of variety. Part of the reason that a great hotel breakfast is such an event is that it reminds us of all the delicious things we can consume for the sake of setting ourselves up for the day. That is before we get into all the potential controversies of how you like your eggs, or whether you prefer eating sweet or savory.
All in all, just because some people think that a coffee is a sufficient first meal doesn't mean we shouldn't appreciate breakfast in all of its glory. It is something that memes are a fan of celebrating, and it is hard to blame them. There are simply too many good types of breakfast.