In-Game Parser.

[Kiara1]

You don't need a parser to have a good performance. Anyone can go to forum, read about proper rotation and train themselves on a dummy to automation of perfect execution. For most people who are underperforming the main problem lies in not that they don't see numbers, but that they are ignorant to the proper handling of their class and no parser will fix this.
The only thing where parser is required when you want to achieve extreme results, but this can be done via teamwork with some PC friends and a whole another level of dedication.

1. People wouldn't have figured out the perfect rotation without parsers to begin with.
2. Isn't it a bit weird that we need to look up how to perform well on the internet instead of learning using an in game tool.