It could be that such altcoins are just shitcoins, or it could be that the effect of Bitcoin pump over altcoins take a longer period of time until happening for real. Altcoins are benefited by Bitcoin's fluctuations, as we have been seeing each new season of crypto market, however altcoins are more likely to perform nicely when we start reaching close to the peak or end of the Bitcoin bullish run.

On the other hand, it's also possible that the trend of the market changed this time. There were many investors hopeful of seeing altcoins gaining 1000% - 10000% in price, so it would mean their chance to get rich overnight. And when many people expect something to happen in crypto market, then it doesn't happen at all. The most profitable opportunities are hidden and not explored by the majority. Once majority starts exploring it, then the opportunity gets dried.