If getting it makes people immune then, why bother with vaccines
Basically it's One and much the same thing! When you have an illness your body will start to make antibodies that fight the incoming infection unless it gets overwhelmed which is what sometimes happens.
However if you already have those antibodies then the body will start that fight before the illness gets establised, and therfore no illness:)
With vacination you are "infected" with a very weak version of the infection so your body makes these antibodies a lot easier and thence you have them next time their needed!
Intresting article here on why ordinary Soap is a very effective anti virus agent:) And works better then the alcohol ones!
www.theguardian.com/commentisfree/2020/mar/12/science-soap-kills-coronavirus-alcohol-based-disinfectants