If we are going to be accurate:

i think since you encouraging others to be grammatically correct,

Should be:

i think since you ARE encouraging others to be grammatically correct,

;)

Your version:

"Since majority of Steemians spend so much time writing in English here, ... "

has a missing 'the' in it:

"Since THE majority of Steemians spend so much time writing in English here, ... "

Your choice of inserting the word 'in' is not wrong, but at the same time my choice to just say 'writing English' is not wrong either (at least to me). My version is just a bit quicker to type.