But that's pretty much indicated in the series.TheMightyOzaru wrote: It's just an opinion backed by the idea that Saiyans are somehow only strong because of Zenkai's and SSJ forms.
When Goku trains in his spaceship on his way to Namek, it's pretty directly stated that ha huge part of his training was because of near death power ups, and high gravity training. Even Goku mentions to Vegeta that he too knows of the near death power up after Vegeta recovers from fighting Recoome. And also, the one way Goku and Vegeta become stronger during the Freeza arc is through near death power ups.
Later, Goku spends his time training with the Yadratians, and Vegeta later trains in 300 times gravity, something we do see him do in the Buu Arc as well. To add, Goku trained in the afterlife at that same time.
We should also include the ROSAT.
The only opportunity the humans have had for any special training is Kaio's planet, and for Kuririn the unlocking of his powers.
And remember when Kaio's said that training with him would increase your strength more than it could do in a thousand years at Earth. So jut simply training at Earth isn't beneficial at all. You need to train in harsh conditions to become better, such as increased gravity or more weights or as in the ROSAT, harsh weather and psychological conditions.
Another very important factor is that he only way for the Saiya-jins to be able to reach Freeza's level was by the 50 times multiplier of the SSJ transformation, and to become considerably stronger they had to reach new forms.
If the humans had gravity training, the ROSAT and the SSJ, they could keep up with the Saiya-jins, but they didn't.
But hey, you can believe all you want, it's fine for me. Everyone is entitled to their own opinion.






