the /USD pair has only one variable; that being the change rate of demand for that coin while the USD stays constant. The /BTC has two variables; the change in demand and rate of change in BTC price. This makes it lag the /USD pair consistently and thus, the /USD pair can often be used as the leading indicator.

There is no technical error in this.

You are censoring by forcing others to see it as you want only. Do you realize that?