i was having great difficulity with the tongue blocking video/lesson that i always had so i just stayed with pucker style all this time.

do you know if the great masters themselves used tongueblockingg, as i thought it used to be a country harmonica techique. ohh perhaps sonny terry used it though ?.

Tongue blocking is an essential technique of blues harmonica - especially the Chicago style. It's a technique that produces a certain sound, and the harmonica's capacity to make different types of sounds is one of it's great strengths. More sounds mean more choices of coloration or nuance to the way notes are played and this is valuable not only in the blues or country music but all types of music. 

Stay with it and you'll get it. Practice and patience pay off!