Some have tried, but it would take some coordinated effort over several weeks at this point to over or underwater the plant. I've found that the folks who consistently vote take it relatively seriously to the point they have discussions about optimal schedules and for the most part stick to them.
I'm glad that these people exist but on the other hand It's hard to imagine what they do in everyday life that this topic is so interesting to them, that they want to feel this responsibility for the plant.
They've also done a lot to enrich the whole community. The daily plant gifs and a monthly voting graphic overview post have been put together by folks in the community.