Your point is true, but sometimes trading most altcoins doe not completely go on with bitcoin up and down movement in whole season, certain times traders buy most top altcoins without btc pairs
Altcoins pairs with usdt, usdc, or fiat pairs would also have impact on most altcoins on the market. I think many altcoins can pump with little btc influence. In short, there is always little altcoins season and I'm hoping it will happened soon.