Elves commonly abuse/neglect their children
Here’s Laws and Customs: “They had few children, but these were very dear to them. Their families, or houses, were held together by love and a deep feeling for kinship in mind and body; and the children needed little governing or teaching.”
Now before you snort and roll your eyes in derision, I’ll have you know there’s an excellent reason for this. Here’s more of Laws and Customs:
“And the Eldar say that in the begetting, and still more in the bearing of children, greater strength and share of their being, in mind and body, goes forth than in the making of mortal children.” [Which is something to consider for us poor mortal girls who think we want to marry Elves.] “For these reasons it came to pass that the Eldar brought forth few children; and also that their time of generation was in their youth or earlier life, unless strange and hard fates befell them.”
In other words, elf pregnancy is a lot more physically and spiritually draining than human pregnancy, therefore Elves don't put themselves through it too many times. They would drain their life-force and die if they did.
And, since baby-making is not something that happens by accident or very often among elves, they’re much more likely to cherish the children they do have.
Think about it: there’s no such thing as “giving up your life for parenthood” for elves - they’re immortal, and as soon as their children are grown and gone they’re free to spend the rest of time doing smithcraft or music or lore&languages or weaving or whatever.
Now obviously there are exceptions: Eol, Aredhel, and Maeglin immediately spring to mind. To a lesser extent, so do Finwe and his three sons. And all elf families probably do have some level of imperfection because elves are imperfect beings. But “imperfect” is a long way from Kardashian/Kennedys-level dysfunction, and many fanwriters don’t seem to realize that.
TL,DR: Elf children take way too much effort to produce to be neglected or abused very often.
