I hear this often, but I'm not at all convinced it's true.
And even if it were: Children will eventually grow up and have to manage their non-cash finances at some point. Why not teach them early?
I've had a checking account and debit card since I was 10 years old, and subjectively this has only contributed to being able to treat "abstract" and physical money as exactly the same from a budgeting point of view.
> It's great for gifts
For in-person gifts. Sending it in the mail is usually a bad idea, as I've personally experienced too often in my life.
Also, at least in the US, there seems to be some weird stigma against cash gifts that's created a huge industry of Visa/Mastercard gift cards with horrendous fees and a high chance of falling victim to some kind of scam.