Yardrat training implies Goku had an unfair advantage over Vegeta all this time. Turns the narrative of Goku just being better on its head, and makes it look like he only had access to better instruction.
If Goku never went to Yardrat, or if Vegeta had access to that same training, the entire series could have been different. They even complimented Vegeta on doing better then Goku did with his ki polishing.