It’s a thing but your order execution won’t be as efficient as an ETF, so you will be losing a non-negligible amount each year in slippage from the large number of small transactions
Unless you're over trading (which is not the goal) you'll pay very little because you're buying and not selling for several years. This will end up being less than the fee you pay to the ETF every year.
> It’s a thing but your order execution won’t be as efficient as an ETF, so you will be losing a non-negligible amount each year in slippage from the large number of small transactions
Not necessarily
ETF managers execute block trades outside the normal market, sometimes through dark pools, not even reported to the public.
Fidelity, Vanguard, etc ask JPMorgan, Goldman to execute these block trades and pay them a fee. This fee can exceed the “slippage” a retail investor can face.