I have long suspected this, though it’s a minority opinion on CC. The top colleges have done a very good job of scrubbing their admissions websites clean of overly revealing data, but data from several years ago suggests that rank is quite important at certain schools. When detailed data was last available for Penn, for example, the admit rate for vals (~40%) was higher than for sals (~30%), and both admit rates were considerably higher than for those in the top 5% (~18%). Those numbers, if you halve them to account for increased selectivity, are precisely in line with Brown’s admit rates today – ~20% for vals, ~15% for sals, and ~10% for other top 10%, respectively.
Of course, one could argue that higher class rank correlates with other factors – a valedictorian might be more likely to have high SAT scores, lots of extracurricular activities and leadership, major awards, etc. Perhaps that accounts for differences in val/sal acceptance rates; perhaps it doesn’t.
In any case, as admit rates at the top colleges spiral ever downward, things that used to provide more of an edge (perfect SAT score, valedictorian status, etc.) are now merely slight tip factors. As others have noted, you shouldn’t fixate on any one factor.