>why do maintainers even argue with people
Because they don't want to be seen like assholes, who just blindly dismiss PRs, and because they take the technical discussion about the PR in good faith.
On some of those PRs the AI agent (?) did not really pressure - it reacted promptly with changes and more plausible (hallucinated ?) technobabble why the PR is needed.
It can be quite hard to discern this behavior from a new contributor to the project that might be a domain expert on something you are not. Possibly with the exception of reacting far too quickly & enthusiastically compared to real people that might have a life.
Honestly most places on the internet are not places to go into arguments in good faith. Maybe it used to be different, but with the amount of OSS projects being endangered by AI slop contributions, silently closing PRs should be the norm.
If someone gets emotional about their PR being rejected, well... its kinda their issue.