The only counterargument against parsers is the "potential toxicity" they can create, but even this can't be applied in dummy parsers because it would be a very own personal thing.
I've been wanting to test my DPS for ages and test different stuff, such as how much an i230 SCH can pull, or the difference of damage between a minuet BRD and non minuet one (with one test involving the use of empyreal arrows and iron jaws and the other not), or the difference between the BLM Fire IV rotation and the standard Fire rotation from 2.0, in case I mess up Enochian I know how much DPS I'm losing out.

But you know what...I play this game on the PS4 and all I can do is assume xd. I don't really understand why this hasn't been implemented yet, it wouldn't hurt anyone and I'm sure many like me would love it...