As TheMikado explained, there's no impetus to rationalise how these U6 Saiyans are surpassing primordial universal dangers such as Buu with nothing except their worldly tribulations functioning as an experienceable trauma used to bolster their own power. Universe 6 doesn't suffer from the same corruption or powerful malevolent crises. Whatever evolutionary power growth they experienced would not coincide with the environmental stimuli that's around them. Moreover, in responce to the allegation of me proposing they only rival Nappa in strength, I might actually feel inclined to agree, at least for the common unremarkable U6 Saiyan. Nappa is classified as a mid-rank Saiyan, so for the U6 Saiyans to be inherently comparable with the likes of him when they have not been forced to endure the brunt of physical adversities like U7 Saiyans have I think is being quite generous. "Prodigies" like Cabba and Caulifla can be reasonably bequeathed with higher power levels. It should still be nowhere near what even the non-Saiyan Z-Warriors have acquired, though.
This was the quotation of yours I was disputing, "So then are you saying you want them to be utterly helpless? To be extremely weak and meek? What's the point of that? Caulifla and Cabba aren't just side characters. Cabba, Kale, and Caulifla are also our protagonists, then why should they be made completely useless and weak? Why would you want Caulifla and Cabba, arguably the Goku and Vegeta of Universe 6, to be weak? They're protagonists, they can't be weak."
You were directly correlating inordinate amounts of power with storyline viability, even going so far as to parallel them with Goku and Vegeta. You and I have either different perceptions of "grounded" or this dilemma with inflation isn't a concern as impressions at the tournament are more important than trying to salvage whatever cohesiveness this power scaling has. I'm claiming they can still battle the ranks of other universes to eliminate them without singling themselves out for noteworthy competition in the eyes of Goku and Vegeta. It doesn't require unbridled metric tons of strength that make Buu look like an ant for them to have meaningful roles in the elimination of other competitors.
RedHeat: How about dazzling us with something other than power? Use Hit's alleged know-how of Shitatsuki to attack the most sensitive and vulnerable parts of the body, some of which can't be strengthened -- larynx, trachea, temple, ears, behind the jaw bone, eyes, and ect. I referenced this possible exploitation of pressure point vital areas in another discussion asking for our impressions on a potential "Hit vs Jiren" confrontation.