I think the point is, you have to conflate them more and more the farther back in time your inflation calculation tries to go.
Some things are pretty much the same today as they were 200 years ago, like land or a person's time. Relative wealth--relative to your surrounding society--allows you to buy those. That was true 200 years ago, and it's true today, although it might cost you a bigger pile of nominal currency (e.g. more British pounds) today than back then.
But no amount of wealth in the early 1800s could have bought you a 6-hour journey from London to New York, NY. Whereas, today it is something that many people can afford, at least occasionally. No amount of money in the 1800s could have bought you high-fidelity recordings of all Beethoven's works that you can carry with you anywhere on your wrist.
So which category better represents inflation since the early 1800s? In terms of things you could buy back then, like land or people's time, you can do a pretty straight calculation. But when you get to brand new categories of things to spend money on, like penicillin or an electric scooter trip, you're essentially "dividing by zero" because these things did not exist at all back then.
You have to invent some sort of way to value a thing in past dollars that could not have actually existed at that point in the past. The farther back you go, the more it just becomes guesswork.