I don’t think everybody is ready to get married in their early twenties. One reason people might rush, though, is because many men want young women. So, although theoretically, twenty five might be young, a woman of that age might be passed over much more often in lieu of women five to seven years younger. That puts real pressure on women to begin the search earlier than they might be ready.
We were also told by a rav of ours in seminary that it’s preferable for a woman to marry younger, closer to the time she’s in school, because she’ll more likely be influenced by her sviva and will be stronger in her yiddishkeit and will choose someone stronger in theirs (this was a bais yaakov sem, meaning, people who would still have the supports of their families outside of sem could still be pulled down by outside influences once they leave school).