Originally Posted by
Hazard
It's sort of complicated and depends on who you ask.
Here's my take of it.
Roshi's moonbusting is valid.
At the same time Roshi's moonbusting is non-indicative of the fire power of the other fighters during that time period and even later.
Ki attacks like the Kamehameha can let you focus your power for a much greater destructive output that you'd otherwise be capable off. We know that from the Raditz fight where Goku's power level shoots up when he fires a Kamehameha.
A regular Kamehameha from Roshi does that for him. Lets him focus his power.
A regular Kamehameha from Roshi back then is only even with a Kamehameha from Goku who is nowhere near moonbusting.
The Max Power Kamehameha is different. The guy bulks up. Considerably so. It's pretty much a partial transformation, granted only for firing that thing.
We can assume he amasses a considerably large amount of power and gets better results than with a regular Kamehameha. At the cost of a noticeable charge time.
Basically, Roshi is plain better at gathering ki. Even when other characters do outclass his 'regular mode', they still won't be able to get the same explosive results from their energy blasts because they can't gather and focus their ki to the same extent as him.