Two rules of pronouns would be broken in Abwx's post.
1) Pronoun antecedents should never be ambiguous. Everyone should instantly know what "it" refers to. Consider this sentence: "After removing the CPU from the motherboard, Joe NYC sold it." What did you sell? Will everyone agree on what you sold? Probably not. The "it" could be the CPU. The "it" could be the motherboard. No one knows exactly what you sold from that sentence. Thus, the Joe NYC selling sentence broke the ambiguous antecedent rule. That is the main problem we are talking about here. There were multiple possible processes that could have been implied in Abwx's post.
2) The pronoun's antecedent should be close by. The antecedent should never be in a previous chapter, previous page, or even a previous paragraph. An antecedent could be in a previous sentence, but only if clear. Look up far away antecedents. Here is one reference:
https://www.trentu.ca/academicskills/how-guides/how-edit-your-writing/grammar-and-style/pronoun-agreement-and-reference#:~:text=Every pronoun should refer to,noun the pronoun refers to.
Or another example:
https://www.dummies.com/article/aca.../positioning-pronoun-antecedent-pairs-190485/
Rule #1 was broken; there were multiple antecedents. Anyone who applies rule #2 of being close by will be mislead since his antecedent was both the furthest away and also in a different paragraph. Being the subject of a sentence has nothing to do with properly using pronouns.