I don't believe so. At best it means perhaps your parents knew how to manage wealth. It doesn't imply the child inheritors will manage it well, or better than anyone else. At worst, it might simply mean the parents had so much wealth they were unable to spend it all before dying, and so some of it went to their offspring.
Trusts, when set up correctly, can do so as well.
Once inherited, the first $90,000 (married couple) of qualified dividend income is tax free. Plus, standard $29,000 (married couple) deduction means that the first $119,000 of investment income can be tax free. You will see the wealthy either try and start a company or not work. Why work a job where about 30% of your income is taxed when you can stay home and not work. If you inherit your parents' home, you can easily live without working.
Current safe dividend yields are about 6% so all it takes is inheriting $1.5m. There are 24 million millionaires in the USA so there may be quite a few that take advantage of this. When the wealthy start giving their children their inheritance while they are still alive ........
Currently, you can give your children up to a total of $12m combined in your lifetime, before taxes have to be taken out.
> but being bequeathed a sizeable inheritance in the first place at least implies that one's attitude to managing wealth has already stood the test of time
I think twice in two paragraphs you managed to conflate the person leaving the inheritance and the person receiving it. The "unearned" part of the unearned boost is clearly only available to person receiving an inheritance, rather than the person who bequeaths anything to the next generation. A person being bequeathed an inheritance does not imply anything about that person's attitude or aptitude.
That unearned boost is already available to anyone who manages to bequeath sufficient amounts of wealth to the next generation, and conversely becomes unavailable to those who squander that wealth instead. That doesn't really change all that much if you introduce redistribution: either way, there will always be plenty of kids who will spend the money foolishy, and forfeit that "extra boost".
It's a very hard problem to solve because it involves people's culturally ingrained attitudes; but being bequeathed a sizeable inheritance in the first place at least implies that one's attitude to managing wealth has already stood the test of time.