It does not always takes long time for all the coins. For example just consider ETH. It has grown enough in the past 3-4 month. From 200 USD to 450+. What else one can expected from any kind of investment.
Remember that Ethereum found at 2015 to be recognize in the community and in 2016-2017 was really a great day for ethereum. You probably did not know that, just don't judge something from the short time.
for new comers, it is the safer way to invest on old altcoins cause those are already proven themselves and still going ahead with theirs best ideas. no doubt about the performance of those altcoins & considered as safe. New altcoins may goes wrong for beginner, as because they don't have privious expriance about that matter.
Not all of the new altcoins are bad and also not all the old altcoins are safer to invest. Do a proper research on everything, just don't do a blind pick even it's on the top one. Know your place and the right time to invest is a crucial stuff to think about.