(when managing the existence in Appleworld was simple, dare I say, "It Just Worked."
And passwords used to be safe at 4 characters. Bread used to be a nickel a loaf.
Things change.
Systems get more complex. More bad guys out there with more things to compromise and steal from you.
Apple IDs have evolved, for good or bad, into personal identifiers, like a phone number. Sharing them, while absolutely possible, is neither supported or advocated.
You obviously are young in the Apple universe. If you don't know what "iTools ... free for life" means, then you have no clue what we family leaders have been managing for 10 years.
If you still begrudge a decision made by Apple almost 20 years ago... not sure what to offer.
Find a better system and use it.