I read somewhere that the whole reason older recipes even work with scooping is because flour settles and gets packed down over time, so your grandma's flour might've been looser than yours straight out of the bag. Kenji Lopez-Alt did a thing on this and found the same cup of flour can swing from like 120 to 150 grams depending on how you scoop it. That gap right there is enough to wreck a cookie batch, which matches your 40 gram difference. Your grandma's not wrong that it worked for her, it just worked because she did it the same way every time for 50 years. A scale takes that muscle memory out of the equation, and for anyone without 50 years of practice that's a good thing.

Wait, so you showed up to somebody's house, they had their own rules ready, and you're the one who got upset? The host has been running that game night long enough to laminate a sheet, which means their group has a whole way of playing that works for them. You brought your copy of Catan, sure, but nobody asked you to run the show, and saying you'd rather play base game basically told everyone their version was wrong. Trading roads sounds weird to me too, but it's their table, their call, and a guest pushing back on house rules comes off like you think you know better. If you want base game so bad, host your own night and hand out your own laminated sheet.