You really don't know anything with that, when you are just looking at the altcoin prices.
Why? Because it indicates their performance relative to Bitcoin, so if Bitcoin rises and alts rise too, the first thing that you have to look at is their price change in BTC - when it's negative, it means that BTC outperforms them, and the opposite if it's positive.
Bitcoin is often called the king of crypto, and rightfully so - it's more stable, more safe, has higher volumes than any other coins, so when you invest in alts, you absolutely want them to outperform BTC, otherwise you are taking unjustifiable risks and get lower profits.
But the problem is almost everything in the world is valued against Fiat money. Buy a pack of milk, biscuit, ride a metro, order a burger, receive your salary, pay your bills, almost all of them are defined against Fiat. And all of the Fiat are defined against USD. So, this loop created by the IMF and world bank is hard to break.
You've completely missed OP's point... They're saying that you cannot gauge the performance of alts by looking at the USD price, since those will automatically increase whenever BTC goes up.
Since pretty much all coins are traded against BTC.