From what i've seen antutu is a collection of many, many cpu or gpu or memory intensive operations wich give a result and we know the higher the result is the "better" the performance is in some way. This is what benchmarks have ever been from the born of computers. We should of course know what these operations are in order to judge what the hardware is capable of wich things and at wich degree. The things you name as "real life scenarios" are better represented by other benchmarks such as PC Mark for example, at least in theory (they can be cheated or abused). In fact, among pc mark suite of tests there one that calculates the time in wich the phone copies a slice of web text, drops it in a text box and calculates the result of the search. This for example represents the speed at wich you do normal operations like browsing. The ux value of antutu however should be in fact an indicator of user experience, that is the smoothness of interface and general smoothness of the phone system i think, or somewhat like that (very much scientific lol). That said i don't think the snap outperforms the bionic especially considering the difference still in cpu department, that is not negligeble, around 7 % if i'm not stupid today. It's nice to see the same difference in favor of qualcomm for the gpu test altough i think it's not as evident and significant as the difference in cpu performance but again it's nice to see qualcomm pulling ahead in gpu power. Finally after years in wich the cpus were far apart with apple being first with an advantage of 40 or 30 or 25 %, it seems that now qualcomm can use a lot of power. I still don't see the reason why wasting the space on the die for lower performance cores, it seems like you can't make a balance or optimise efficiently high performance cores to me. Also you have to wait for other benchmarks that describes all the aspect of the phone still.
The Snapdragon 8150, Kirin 980, A12 Bionic, and a few other SoCs were intensively tested on AnTuTu, with the results showing the Snapdragon 8150's overall dominance. The A12 Bionic managed to hold the high ground in a few departments, though.