I was 23 when I had my first romantic relationship.
Not dating in high school was fine for me because most of my friends didn’t. Then in university more and more people paired up. I became miserable not because I was lonely, but because I felt inadequate. Much like failing to get a part-time job or pass your driving test, I felt incompetent because I didn’t live up to society’s standard of what constitutes a functional young adult.
So I think there is some truth to late bloomers being more anxious, not because there is something innately wrong with them that causes them to remain single, but because of societal pressures. If we stop centring dating and getting married and having sex as the Ultimate Goal in human life, a lot more people would be less anxious.
Just my two cents.