actually there is notthing strange about this, altcoins have always been dominated by btc since the first time they were born, btc's value is too big that it has controlled the market all the time, and every year, there will be a time when altcoins is dumped because of BTC dropped, so altcoins can never get out of BTC's control as long as BTC is still the best cryptocurrency on the world.
yep. BTC _is_ crypto, so it only makes sense that promisecoins riding its coattails goes down if it turns bearish.