Yes, this breadth-first description is a good way to characterize my reason for having lots of tabs (though I don't have nearly as many as some people here say they have).

One additional factor is that I think I was trained to do that by slowly-loading websites. If I open a site in a new background tab, it can go about loading as slowly as it wants, and it'll be ready by the time I get around to reading it (I guess this would be ruined by lazy loading tabs...).