I agree in principle, boiled onions is the base but I think we all agree that it can be expanded a little to make the 'main dish' easier to cook.
I have found some Base gravy recipes are better for lamb (more oil), others better for chicken (drier) and some are excellent for fish/vegetable curries (less spiced). I recently made a Balti Base from these forums and the curry was excellent, but it is a base that can only be used for Balti as the aroma and flavour are distinctive. So go too neutral and I guess the 'cooking' becomes longer and whilst that might work for a home and restaurant, takeaways generally rely on high turnover.
A butcher at my local Asian supermarket was trying to verbally give me his family's method of cooking on the last day before Eid last year, but it was long, complicated and did not involve any base gravy (that is a convenience for takeaways I presume) and I got lost in all the ingredients and method. He and I are increasingly familiar and I am hoping I can get an invite at some point in the future.
BIR v Home cooked is a massive thing for me as the best dish I ever had was a home made meal as a reward for working, back in 1994 and it was chalk v cheese compared to takeaways at the time and I still think so today, Boneless Quail in a light gravy with sliced fresh orange and a little bread (roti or a naan not a whole one). If only I could ask them now but the business closed down a couple of decades ago and I have no idea where they are now, or if they are even still alive sad to say.
So I think cooking is not just about replication but also about continuation, learning and passing it on, that is maybe why I am aggravated when somebody says they make 'this' or 'that' and then for commercial reasons mentions a 'Brand' version.
BAJ