Honestly, 3-A Android 17 is far less of an ass pull than Golden Frieza. The former started out stronger, and had way more time. On top of that, he has infinite stamina, so he can literally train non-stop with zero rest and just keep getting better.
Also, another thing to keep in mind. All characters known to go from 4-B to 3-A did it in an extremely short amount of time with some sort of ass pull. 17 would be the only exception. Think about it. The SSJG ritual. Goku goes from 4-B to 3-A within minutes. Vegeta gets SSJB offscreen without the ritual by training for a few months (granted, he was being trained by someone who is 3-A). Frieza gets his Golden Form within four months because he's "a prodigy". Goku Black achieves SSJR in a short amount of time, even though he struggled with SSJ Goku like a week prior. Trunks achieves his Super form out of rage. Future Zamasu somehow became 3-A due to immortality.
If 17 is 3-A, he would currently be the only one who achieved this level over the course of several years.