If i recall correctly the first time a thread regarding SE's concerns on parsers was posted (during 2.0) the question initially came up in regards to a warning a player received for talking about one in game during the course of calling out the DPS (or lack thereof) of another player.
Obviously there is no way SE can know what you do or don't have installed client side without allowing the game to install rather intrusive software to scan your system (there are a few games that do this). However what they CAN do is review the in game chat logs should you be reported for harassment and clearly see if someone says "Well your DPS is X because this program says so" at which point action can be taken.
Those who played FFXI will remember similar discussions about the use of 3rd party programs that allowed you to parse data and see things like party member TP and the same rules generally applied, if there was enough in-game proof of a player speaking about or using one to harass another player then it was grounds for a GM to take action.
SE is likely not to condone one 3rd party program over another regardless of how it functions until they add official addon support to the game, and even then those programs that they do approve will most likely be required to have features that meet a set of guidelines.
This allows them to control what they do and don't want the playerbase to have access to, at which point it can be inferred that any third party game related program that can be used detrimentally (see: to harass) or to gain advantage (see: exploit) will most likely fall under grounds for account action / termination.
This is very much a "Their house, their rules" scenario
Fundamentally i agree with you,
The players that have issues with simply parsing will likely have the same grievances against stopwatches or calculators, as parsing (strictly parsing only) is harmless in what it does as a tool of calculation. unfortunately players themselves are not as unbiased or objective as numbers are and the potential for harassment is a very real thing.
Now while i personally see that the benefits outweigh the detriments when it comes to this we're talking about the same company that once again has disallowed /tells in dungeons for similar reasons.
Ironically though it's hard not to find amusement in the many players who will rally out against the perceived "evils" of parsing out of a fear of being called out or dealing with other players, but will still reap the benefits of those that use them to determine things like optimal rotations or BiS gear setups.
If the perception of this is to change (and it most likely won't) the case will have to continue to be made for an in-game feature to allow us to see player performance (which I'll surely advocate for right along with anyone else).
But as far as 3rd party applications go in this case (parsing / data calculation) it would appear that their stance is clear.





