Hello,
ii-V-I's are so prevalent in jazz music for a number of reasons.
The ii-V-I is something called a cadence. This is a part of the music where it reaches a resting point within the harmony specifically. The traditional cadences are V-I, and IV-I, but sometimes there can be other chords that make the cadence sound stronger. This is where the ii chord comes into play. Using a ii chord before a V chord make the I chord sound more like the key center.
It is specifically found in jazz music, because it is an easy and efficient way to establish the sound of any key, very quickly. Some jazz standards use ii-V-I's every few measures, and use them to change the keys. These key changes add complexity, and interest to the music.
ii-V-I cadences can be found in all kinds of music, from symphonies, to pop music. The association with jazz just has to the with the frequency we hear them.
