Using a visual "proof" to show that $\sum_{n=1}^{\infty} \left(\frac 34 \right)^n =1$

Question

The "proof without words" that $\sum_{n=1}^{\infty} \left(\frac 12 \right)^n =1$ is fairly well known:

But why can't we apply the exact same logic to $\sum_{n=1}^{\infty} \left(\frac 34 \right)^n$ or any other infinite sum of a fraction?

(apologies for the giant images)