Do not be sorry. We are all humans after all. If anything, I should plead guilty of the same. And you are right, after 100+ posts, it is easy to misread, misinterpret or draw false conclusions. Hell, sometimes answering to somebody might mean that an other one posted and invalidate or modify the meaning/intent of the message you were writing. Again, I am guilty of that too. Try as I may, I am not 100% perfect (but sooo close!). Jokes' asides we all make mistakes. As long as we can forget each others, we can further our discussions.
The bad cases usually happen with new players that do not know what is acceptable or not. And in new, I mean new to a table and not necessarily inexperienced. We all come from different experience and what is normal at a table might not be at an other. Many houserules are often forget to be house rules and assumed to be rules. Period. So when a player comes to a new table, his old habits might kick in and all of a sudden... BOOM! A big arguement erupts like a volcano. As I have done many tournaments in the days, my opening speech as DM in chief and organizer was to tell everyone to remember that house rules were just that. House rules and they had no place in tournaments. In one big tournament we had 25 DMs... each with his (and one was a she) house rules. So we all had to be on the same page and we adjusted our rulings accordingly. Me and two others were there to be sure that if an arguement at a table was erupting, we would be there to either support or invalidate a DMs decision. It happened once or twice, that we invalidated a DM. Most of the time, it was a player knowingly or unknowingly applying a house rule to the situation.
The true toxic/abusive player is a rarity. But they are there. Most of the time, it is a nice chap trying to get a small advantage for his character. We are all humans after all.
When it comes to players that "push" a lot of times it's also just a matter of expectations and theme. Take the guy who wanted to have lunch with a god because he was a mid level cleric. After we moved, he tried DMing for a while and based on updates from the group (before it fell apart) it was quite the gonzo campaign with a lot of crazy stuff. Which, if the whole group is in on it and having fun could be cool. But my campaign and all my other players were into a more grounded campaign style (for D&D).
I don't even think he ever even understood that he was pushing the boundaries, he just thought that it was the way it should work and never accepted the limitations. Add in an assertive personality and there were just times we had to take a hard line with the guy because otherwise he just kept pushing. Which is just to say there's a whole spectrum of players, from people who just want to roll some dice to those that feel entitled to a co-DM position because they think their ideas should override everyone else's ideas and opinions.