An interesting case where estate taxes are a problem was recently mentioned by a high school classmate who's a farmer in southern Arkansas: Many small farmers are land rich but cash poor. The property their family has been working for generations is now quite valuable and if they're not making a huge amount of profit - and most small farmers aren't - they won't have enough cash for the taxes to pass down along with the land to their children who will be forced to sell thus ending generations of farming in that family.
That is a corner case ("land rich, money poor" enough to hit the estate tax thresholds) that accounts for almost no family farms. I don't remember the number of people that would be affected by it, but it's very small.
The movement to end the estate tax has invoked that because it's a good narrative, it resonates emotionally, but the numbers don't back it up.
Estate taxes are, in my humble opinion, unmediated evil. Retaxing generational wealth and savings that have already been taxed once as income is unconscionable, and unfairly penalizes those who are fiscally responsible and actually do save.