Is vinegar necessary when making barbeque sauce?

the vinegar helps counter sugar and tomato pasteorsauce sweetness and gives good tang. mustard and lemon juice are also acids that can counter the sweetness. but no food rules here; make your bbq sce as tangy or not tangy as you like. acids also tenderize meat. we coat our pork or chicken
in our thick bbqsce for 1/2 to 2 days ahead of grilling.
suggest:add 1/2 the required vinegar at first, cook sauce and taste; add more acid as your tastebuds dictate.

You can put anything you please in barbecue sauce- the only point is the taste, so if it tastes too vinegary to you it's too much vinegar. Or too little sugar.