In one of Helio's fights, he was thrown something like 37 times. Almost all of his fights before he retired for the first time in the late 1930's were grappling-only matches that ended in draws, and according to many of the descriptions Helio just basically held onto the guy for the entire time. After Helio came out of retirement, it sounded like he was much better. So that begs the question of what/with whom was he training during that time.
Some matches he's dominated, like against Yano, as you describe. Some not.
Helio defeated Dudu, for example, and Pedreira notes that Dudu had dominated George Gracie in their match. Dudu had defeated Geo Omori by submission as well. He's described as a luta livre champion by Pedreira.
Helio Gracie's career in Choque:
1932: Helio's debut against Antonio Portugal. It's not described in great detail, just "a good fight" where both fought with "enthusiasm." Helio wins, but it isn't noted how.
1932: Helio faces Namiki. Namiki is described as dominating most of the bout, but Helio is noted as attacking later in the fight.
1932: Ebert & Helio had what's described as a boring fight. Ebert fails attempts at throwing Helio out of the ring, and tries a submission; Helio attacks with two armlocks. It ends a draw. Pedreira notes Helio is out-weighed, and it's no-gi.
(It's overstating to describe Helio as just "holding on" for the entire match here or against Namiki. Pedreira doesn't write that either time.)
1934: Helio defeats Miyaki by choke.
1934: Helio & Zbyszko have a boring match -- neither attacked much. Zybskyo wears a gi but also has a 30 kg weight advantage.
1935: Ono and Helio have a draw, Ono dominates as you mention.
1935: Helio defeated Dudu by submission -- it's said that Dudu exhausted himself in Helio's guard, and quit after they were stood up and Gracie landed a kick and punch.
(Pedreira notes that Dudu had dominated George Gracie in their match. Dudu had defeated Geo Omori by submission as well. He's described as a luta livre champion by Pedreira -- and 85 kg to Helio's 66.)
1936: Yano dominates Helio as you describe. But even then, Pedreira includes accounts from writers of the day who blame Yano for not engaging.
1936: Ono dominates Helio but fails to finish.
1936: Helio defeats Massagoichi by armlock.
1937, Helio is DQed for using a prohibited technique against Dudu.
1937:Helio defeats Klausner by armlock.
Five wins by submission, six draws, one loss by DQ.
There were times Helio seemed over-matched in these accounts, sure -- and seemed to just survive. But as you can see above, that's not the whole story.
I'm a little wary of people replacing one exaggerated account of history for another.