if you may add an opinion, it's one of them because there was a big fluctuation in altcoin in 2018, and also in my opinion why Altcoint today is very slow growing, yes because there has been a transformation from ICO, Crowdsale to IEO, which exchanger and organizer are united there, and if a new project wants to use the IEO system, of course, it must meet the requirements and standards imposed by the exchanger itself.
and it is very big impact for the development of Altcoin, especially altcoin era under 2016, very lucky for altcoin which can still survive because it has a strong community.
The biggest fluctuation actually was in 2017, to me. That was when x100 was very common for alts, and some even went x1000 or more. Bitcoin itself as we all know went over x20,,, which was the true reason for everything else getting pumped.
That year along the pump, went several crashes. I remember ETH got to $400 like 3 times and crashed before going to 1k. That made a lot of money for a lot of people!