Why do you think the outcome would be different compared to me popping off on someone over dropping to every boss mechanic? That's also information provided by SE. I can see when someone dies, I can see their (stacking) weakness. The reason why people are so tame in ff14 is because there is an actual threat of punishment for every single aggression. This keeps people quiet right now, it will continue to do so because people are already used to that.
Do you really think people dont already see if someone deals no damage without parser? That's foolish. If I see a dps be fourth in aggro on a dungeon boss with no deaths happening well into the fight, I dont need a dps meter. Do you think people dont notice a trash pull taking double the time than usual with one dude standing there and only acting every 5 seconds? Do you think people dont notice a healer not casting a single dps spell the entire fight? If you open your eyes you already see that but people are overwhelmingly quiet about it.
Nothing would change, which makes your next question actually really good: "for what?" This is the only valid argument in this entire thread. The benefit would be to be able to show people going on a condescending rant about how much they are carrying a party if the blame game starts happening that actually they werent and that definitive proof exists. If this upsets people who want to get through dungeons with pressing no more than 3 buttons then good, they're not respecting anyone's time, why should their time get respected. That said, I dont think it would be a good idea for SE to build their own tool. I'm sorry console players, you wont be able to use ACT and I dont think it would be a worthwhile adventure for SE to try to copy it.
It would be a huge waste of time, what would be the far more sensible approach would be to dial back their stance on mods and not outlaw them on principle. None of the TOS about harassment would have to change because it's already covered. Even now, if you pile on someone for their damage numbers ingame it's not mod usage you get punished for. It's harassment rules. Under the current way of handling it.