I often wonder whether the BIR curry base was invented for the UK market by Bangladeshi/Pakistani chefs or whether a restaurant in Bangladesh/Pakistan would use the same technique for fast cooking.
One thing is for sure - it would be impractical to make a BIR base without a blender. From this perspective is cannot be seen as traditional Indian cooking.
I've tried (over many years) cooking Indian food as per the usual: Fry onions, cardamom pods, cloves, bay leaf, cinnamon etc. add spices, fresh tomato etc. I've never cooked a dish like this where the sauce tastes as good as one using a base sauce, and I'm not mad keen on eating whole spices either.
For me the BIR base sauce technique I learned from this forum has transformed the dishes I can make and I don't think the technique should be considered second-rate compared to traditional Indian food.