UJM,
I don’t know (but I suspect) that natural immunity is more robust than the vaccines in preventing future illness. However, it is also the case that someone who has had the disease before will increase the level (or chances) of their immunity by taking the vaccine. The question is whether the risk of taking the vaccine is greater than or lesser than the increased protection of the vaccine.
I don’t think that the data is clear on this issue. But I suspect that there is a substantial difference between people in their 20s and 50s on this. And a person’s health otherwise matters also.