Since 2013? You could count a few altcoins seasons that have boomed since then, altcoins weren't even so popular until the recent hype in 2017. Sadly, with all the hype also came so many opportunistic scammers that took advantage of new people in crypto. My opinion is THERE ARE altcoin seasons, nobody can tell if the next one will be as huge as the previous ones, but time will come when at least some of these altcoin projects will finally be realized.