Sure, in theory, in practice there's all sort of physical constraints on the hardware that add/depend on each other and whose complexity "grows" (I'm abusing the term, I know) much faster than linear, hence why I used the term exponential.

"Quantum mechanical states are extremely fragile and require near absolute isolation from the environment. Such conditions are hard to create and typically require temperatures near absolute zero and shielding from radiation. Thus, building quantum computers is expensive and difficult. The challenge increases dramatically with increasing size (number of qubits and the length of time they must be coherent) and thus only small to medium scale computers have been built so far.", from [1]. Also, I recommend reading out the whole article as it gives a nice, broad, overview of the challenges in place, it's not as easy as putting 1 qubit + 1 qubit together.

1: Quantum Computing: An Overview Across the System Stack, https://arxiv.org/pdf/1905.07240.pdf