I'd have to agree. Pretty much all of science starts from anecdotal happenings that someone wants to put to the test. I've done chickens for 40 yrs and have given grit a time or two but mostly not at all, whether the chicken was confined or free range.....in the end I've never seen a bit of difference in performance or health.
I've never had an instance of sour crop either in all those flocks and all those years, so you can call it anecdotal or not, in real life and on real birds over a long span of time, buying special grit for chickens and particularly chickens of different ages, etc. is pretty much a waste of time, worry and money. It's not being cheap, it's called being practical and logical.
Now, if a person had a commercial operation where the chickens never saw the light of day or hit soil with their feet, I'd say grit might come in handy....depends on the feed they are given. Mostly, though, grit is not really all that necessary unless y'all are feeding whole grains or dry mash to confined birds, but pelleted feed doesn't need much grinding at all.