If the target's traffic is going through the MiTM, then can't the spoofer find a way to just not traffic the connection? Or traffic the connection very slowly? Over all what I'm asking is that instead of a MiTM attack being for traffic analysis, could it be used to simply block a connection?
In the common understanding of a man in the middle attack, the attacker can actively tamper with the traffic, i.e. not only passive sniffing. There are typically no limits assumed of what exact modifications the attacker can do, which also means that they could simply drop the traffic and thus block communication.