Why not? All you need, technically speaking, are devices for measuring and weighing small amounts of material fairly precisely. The ability to do that was not significantly greater in the early 1800’s when Dalton and Avogadro succeeded in reviving atomism.
I used to think that the Greek atomists just had the rotten luck to live at the same time as two of history’s greatest philosophers, Plato and Aristotle. Atomism, though right, lost the dialectical battle.
I now think that western philosophy tacks between two strategies for explaining What Goes On.
One strategy explains the properties and behavior of entities by appeal to composition: the properties and behavior of the fundamental objects that make the entity up. Call this strategy ‘Elementalism’.
The other strategy explains the properties and behavior of entities by appeal to their kind: and a full understanding of the essential properties of the kind will explain what the entity does. Call this strategy ‘Formalism’.
Formalism dominated from 400 BC until 1400 AD. Our course in early modern philosophy is the story of its overthrow by elementalism in the Scientific Revolution.
Either strategy yields philosophical problems, problems which the other strategy tends to solve – at least for a time.
The main problem besetting any elementalism is composition.
Matthew hits a baseball toward the house and breaks a window. 
Elementalism explains this by the bonds which hold atoms together into molecules: the molecules forming the baseball (B) and the window (G). The velocity of B on G is sufficient to disturb the molecular bonds of G.
This explanation makes no reference to the baseball, the window, or to Matthew. What matters for causal explanation is what goes on at the level of B and G. Baseballs, windows, and teenagers with poor judgment may as well not be there. Since we need not countenance them in order to make our best (elementalist) theories true, we can be anti-realists about macro-objects.
If we wish to believe in baseballs and grandchildren – and we do – we could suppose they supervene on the fundamental particles. But then they're epiphenomenal: their presence makes no difference in the world.
If they’re to make a difference, we seem to be committed to saying not only that “Events involving B cause events involving G,” but also “Events involving the baseball cause events involving the window.”
But that gives us two causal relations: double determination. What goes on is over-oomphed.
Indeed, since we have many levels operating:
- macro- (baseballs and windows)
- physiological (Matthew’s hitting the baseball)
- neural (events in Matthew’s brain causing his motor movements)
- mental (Matthew’s ill-considered decision to hit the ball toward the house)
Here’s the dilemma.
The higher-level events purportedly involving higher-level entities are not, strictly and literally, real events at all, or derivatively real.
But then they would be entirely epiphenomenal – not really part of the causal story of the world.
They are real, with their own causal relations.
But then ‘what goes on in the world‘ is over-determined.
In short, the constant dilemma with elementalism is that it threatens to give us either too little reality (no grandchildren) or way too much. Indeed, since there may be no limit to the number of levels at which causal explanation can take place unintelligibly too much.
But we thought elementalism was superior as an explanatory strategy.
Does formalism do any better? Arguably, yes.
One promising formalist strategy currently emerging is a revival of Aristotelian-style Hylomorphism. Robert Koons gives a nifty summary of the current state of this research project. 
On Koons’ version, the causal powers of a substance’s parts become powers of the whole substance, and so the over-determination problem doesn’t arise:
“(I)f I stand on a scale, is it I (as a whole) or my parts (collectively) that cause the pointer to move? If the powers associated with weight have migrated from my proper parts to me, my weight can be the unique and non-redundant cause of the scale’s response.” (Koons 2014, 8).