I think some say it's important and some say it's not important.
That's my opinion, back to each person's taste.
whether altcoins or bitcoins all have their respective roles, in my opinion.
It's up to us to see what it's all about.
Every person cannot think alike and it is not possible that every person will think exactly same as other thinks. In my opinion altcoins are good as well as bad depends on their nature and rate of success.
You can get benefit from altcoins if you search well that which coin is Suitable under such conditions. Take Solana as an example that it was not a successful coin in past but now as its rate is increasing so everyone wants to make investment in it. Same is the case with other altcoins if you find a coin successful then don't hesitate to invest on time otherwise you will miss the opportunity.