Each person trading and investing in a cryptocurrency must decide for himself whether to trade or hold altcoins.
I have an investment portfolio in which there are altcoins and I periodically sell them and buy new ones.
You can combine trading and holding - I do not see any problem here. Pick the altcoins with low market capitalization to trade them, and hodl such cryptos like Bitcoin, Ethereum, Monero.
In this regard i do agree with you that here are so many Alt coins we can choose the best and the one we like the most. Trading and holding is another issue but I truly love holding as its easy way of making money and its safe. Trading is good for long term and increase your knowledge about trading through actively participation.