BTC being the major trading pair of most of the coins in the market will always have its effect on all tokens. Since tokens are mostly traded in terms of satoshis, so when BTC price in FIAT (USD/EUR) goes down, it makes satoshis value go down as well and eventually the price of other tokens as well.
On the other side, during the past few quarters we are seeing a lot many coins are also getting FIAT pairing on exchanges this will reduce the BTC impact on other tokens but it will take time.