Disclaimer, I am 1) talking about the US and 2) talking about the current laws not what I think the laws ought to be.
You have to pay taxes on income.
You also have to pay taxes on gifts.
Say someone gifted you something incredibly valuable, like a house. You have to pay taxes on that gift.
Say you don't have the money to pay taxes on the gift, then what?
Say the gift-giver of the house is also willing to pay your taxes.
That would ALSO count as taxable income which you would need to declare and pay taxes on.
Essentially, it's illegal to give things to people whose cash on hand is below a certain threshold.
another part of the reason is that money is power, and building generational wealth dilutes the power of the current elite class. taxes are a very effective way to put a very strong downward pressure on effective, exceptional people originating in the lower classes.
Note how the Jewish intellectuals completely ignore this point and propose various economic systems, from free market to communism, which rely only on individual self interest.
But even the Marxian socialism does work. It took a country back in the stone age, Russia, and turned it in the second world superpower.
The meme of "socialism/communism doesn't work" is just a stupid meme popular among boomers.
Generosity in capitalism, and not cronyism and hoarding of resources should be encouraged. If you look at the US system, there can be no generosity, because it is too controlled. True free market without government ties is the way.
Socialism also doesn't mean maintaining parasites. Everyone is required to contribute to society to the best of his abilities in every serious political system.