That has been my experience and I actually have data to back it up. I'm a test subject in a antibody study. I'm the lone Indian who had the J&J shot and then a breakthrough infection. I now have 96.22% neutralization against Alpha and 96.03% against Delta which is more than 2X higher than just the vaccine alone. Feeling pretty bullet proof for now.
There is a guy in my group who is testing at almost 90% neutralization a full year after natural infection....no vaccine. That is significantly higher than most with natural infection only. The thought is that he was recently re-exposed and simply didn't know it. His immune system ramped up and took care of the virus.
That graph is very interesting.