My spreadsheet factors in Roth conversions, taxes, the SS haircut, IRMAA, a house sale, paying taxes via IRA withdrawals, etc. It is pretty complex. I am always maximizing for net worth at age 90 (I had to pick a number, and based on our parents' lifetimes, 90 seems reasonable), due to our desire to pass as much as possible on to our DD.
Anyway, it always says to take SS at 70, no mater whatever other what-ifs I tinker with. Just for fun, I changed the ages to 67 (FRA) for both of us (since we are 65 and 66, any earlier does not matter anymore). The difference at age 90 was $98K, or 1.18% less than both age 70 withdrawals. And, if I change it to me (the higher SS amount) at 70 and DW at 67, the difference is $58K, or .71% less than both age 70 withdrawals.
So, those are just not huge numbers, especially if you divide them by about 2.4, for projected inflation. I am sticking with 70 for both of us, for now, but I can see how some folks would say it does not matter that much, and want to have the comfort of that monthly check earlier.