Because sulfur cubes can grow back when split and always split into 2, the number grows exponentially with the rate of 2^n, meaning you can go from 1 cube to 1024 cubes in 10 cycles!

Because of this the more you kill the faster these number increase, in a few days you could easily reach hundreds of thousands, meaning not only they're great for xp farms but also introduce the potential for a very strong lag machine with barely any effort. You just have to put a cube in a 1×1 and put powdered snow above them and you got a fully automatic lag machine that becomes worse exponentially.

WARNING: LAG MACHINES ARE PROHIBITED ON MOST SERVERS AND CAN LEAD TO PERMANENT BAN AND MAKES THE EXPERIENCE WORSE FOR OTHER PLAYERS. USE AT YOUR OWN RISK