I, too, think that your co-worker has a valid point. In a situation where you just want to float a fixed number of <div>s next to each other, float might be the better choice. Flexbox shines especially when you do not know the number of elements and rows/columns they will take up. So let me make a real-world example: vr-zone. They could use float for their menu bar at the top, but they might want to consider flexbox for the marquee effect of the news articles (in fact, they use JS, but that's not of interest for now :D )