Why analysis of Aloha protocol uses Poisson distribution? Pretty much in all of the analysis of the Aloha protocol that I read, it is assumed that the distribution of packet arrivals is Poisson. What is the rationale behind it? Isn't it actually binomial distribution that is approximated by Poisson because $n$ (number of users) is large and $p$ (transmission probability) is close to zero?
IMO, the biggest reason is that Poisson distribution is more tractable mathematically. Some experimental studies claim that it does follow Poisson. However, there are also other experimental studies show that it does not. 

Mathematically, Poisson distribution can be viewed as the approximation of binomial distribution under certain conditions. However, it is not the rationale behind the Aloha protocol. 

As a mathematical model, you should consider your own scenario carefully and decide whether to use it or not.