Yea judoka had no striking game and boxer had no wrestling game. Under these conditions the grappler could just wait out the striker until catching a grapple, then win. This is why the Gracie family pushed UFC in the 90s, because karate-and-boxing-obsessed US audiences were constantly surprised by these matches, and it led to more people signing up for Brazilian Jiu Jitsu!
Yea that wasn’t meant to downplay the skill required to hang. But relatively speaking, defending with a goal to clinch up takes a ton less effort and risk than pursuing an offensive striking game.
Looking from the other direction, it is incredibly difficult to actually knock someone out who is only defending and waiting to get close to you.