Hi Ryan,
I think there are three reasons why people put counter-weight down the shaft, one being unaware of how it can impact guiding, second some may not have enough counterweights and lastly some may not care as it does not significantly impact
their mount for what it is being used for.
Here are a few words from a premium mount maker about counterweight positioning:
https://astro-physics.info/tech_supp...ze-guiding.pdf