The point is that the question of "mostly meritocratic" is nonsense because it depends entirely on the definition of merit. If you call genetics a component of merit then society becomes much more meritocratic. If you call it not then it becomes much less. But it isn't society that is different in either case. You can make any society arbitrarily meritocratic or unmeritocratic by classifying various things as merit or not.
And this gets into the whole question of free will. If you had the "opportunity" to be taught about expected value and opportunity costs and economic theory, do your choices that take into account that knowledge count as merit or opportunity? Did you make the choice, or do your circumstances cause you to?
But those kinds of games aren't revealing anything deep, they're just shuffling paper around. It's a shell game used for political advantage to try to create a conflict between things that shouldn't.
Rewarding is merit is good. If there is a law that says people can't keep enough of what they earn, that is a dumb law, because we will lose good entrepreneurs.
Increasing opportunity is good. If there is a law that says black people can't be entrepreneurs, that is a dumb law, because we will lose good entrepreneurs.
Where politics comes in is that you have people that want to trade one good against the other. So they vilify success to justify reducing its incentives in order to raise money for programs that increase opportunities, even though that is one of the dumbest trade offs available when it is possible to have both. And the rhetoric used convinces people that their circumstances mean that they can't succeed, even though the circumstances only make it more difficult, and then they don't even try.
The straw man is that Gates is a representative example of anything when he is the far extreme outlier. Taxing him at even 99% would generate an inconsequential percentage of government revenue because there are so few people like him, whereas the median family in the "top one percent" is a surgeon who is married to an anesthesiologist. So if you want meaningfully more money, it's really going to come from the large number of doctors and software developers and college professors, not from one Bill Gates.
But the government already raises more than enough money. The problem is that most of it goes to corruption and waste and appeasing the AARP. Use the same money to actually increase opportunities for people and you don't have to take it from doctors and entrepreneurs. (Have a look at what percentage of the federal budget is spent on retirees. Say what you will about the need for those programs at some level, but that percentage is just too high, and it keeps going up. All while the programs are sending big checks to millionaires and inflating healthcare costs. But it's much easier to vilify Bill Gates than anger a large voting block in the major swing state of Florida.)