Please do not be so critical of the math skills of forum users. Otherwise, the forum users will comment on your grasp of the English language.
The sentence is understandable, but the phrasing
"grasps of the math" is not standard English. A more natural and grammatically correct way to phrase it would use the word "understanding" or "grasp" (singular).
Here are a few ways to revise the sentence:
- "Reading this thread, I can see the understanding of math is poor in most."
- "Reading this thread, I can see that most people have a poor grasp of the math."
- "Reading this thread, I can see that most people's grasp of math is poor."
- "Reading this thread, I can see that most people have a poor understanding of math."
The current formulation uses "grasps" (plural) in an unusual way that sounds awkward to a native speaker. Using the singular noun "grasp" or the synonym "understanding" makes the sentence sound much more natural.