Burp Proxy vs MITM

I have recently started using Burp as a proxy for hunting bugs on websites and I see many submissions where people have intercepted and modified requests/responses to exploit certain logic flaws in web applications. However, this is possible only because we have installed Burp’s certificate in our browser that allows it to decrypt the traffic to and from the web application. However, in a realistic scenario, the attacker would have to conduct a MITM attack to intercept/modify traffic. This makes me wonder what the point is of traffic interceptions using Burp.