The scalability issues are the main problem and the current market conditions are not as same as in 2017. BTC first time has crossed the $17k price and the altcoins have followed this route all the way up to ATH. The alt season will bring the big money to the market and BTC price has not reached the top level yet.
At some point people move their investments from bitcoin to altcoins. This time it hasn't happened. This is the prime reason why there is no big growth with the altcoins price, particularly ethereum. Another thing, previously ethereum grew high due to the increased number of ICO that contributed to a massive growth to ethereum. Now that hasn't happened, as people are aware of ICO.