In fact, I was also convinced that all altcoins depend on the BTC rate. But here's a phenomenon I was able to see. Recently, the BTC rate is more or less static, a small increase and a small drop, thus showing a small dynamics. At the same time, altcoins show much more significant jumps, especially the pump up. So whether they depend or not, but the result on the face, altcoins can move up regardless of the BTC rate.
They are showing a good pumped as they experienced a massive dumped before, just like what happened to bitcoin before this barrier, coming from last year high almost $20K and now standing strong between$6k-$7k at most, those alt coins suffer a massive dumped together with btc and the best example to that is ETH itself, though we are seeing 10-50% of increase coming from the alt market but the actual percentage to that from the previous high still comparable with bitcoin value.