No team can reach or win finals without having a top tier duelist.
I mean let's go through all the teams that won international tournaments then.
SEN Reykjavík - Obviously TenZ was insane and had a shit ton of impact
GMB Berlin - D3ffo was pretty insane in Berlin, but nAts and Chron had a lot more impact. nAts even had a higher ACS while playing Viper and Cypher.
ACE Berlin - cNed and friends (although zeek had a pretty insane run that tournament -- notably he did play a lot of duelist as well though, both Reyna and Raze)
OPTC Reykjavík - yay was clearly their star player, and he barely played duelist. Victor was a good duelist, but he's not the type of guy you'd have in your top 5
FPX Copenhagen - mostly carried by Shao and Suygetsu. In the grand final, Zyppan was bottom fragging on Raze for two maps, they played no duelist on Icebox, and the last two maps were Zyppan on Raze and ardiis on Jett respectively, none of which had super insane impact (they both performed well though)
Loud Istanbul - While aspas is without a doubt one of the greatest, if not the greatest, duelist in this game, at that particular tournament, he had the lowest average rating on the team. pANcada was the tournament MVP and each player had insane impact.
FNC LOCK//IN - Derke was very good, had loads of impact. Still outperformed by Leo though
FNC Tokyo - Kind of similar to Loud at Champs, where Derke was good, but Leo, Alfa and Chron were just all better.
EG Champs - I mean the three maps they won in the GF were definitely on the back of insane duelist performances. Jawgemo went ballistic, and Demon1 had an insane Split on Jett. LF was pretty similar with the exception of Bind. The rest of the matches weren't really close and they just hard team diffed everyone else, so overall I'd say it's fair to say that great duelist performances were a big part of their actual win.
So out of the 9 teams that won tournaments, 3 (SEN at Reykjavík, ACE at Champs 21, and EG at Champs 23) were in large part due to great duelist performances, the rest had much higher impact from other parts of the team.