Depends crucially on the exact circumstances, and swords used. For modern Olympic fencing you'd be 100% correct, but for the swords they're using I think the situation is much more muddled. Also depends on the opponent, and whether one is facing eg monsters with a thick hide.
But I'll grant you that economy of movement is by far the crucial thing. That's what you meant by “finesse”, right?
Economy of movement is one thing. Actual finesse, meaning agility and quick, unexpected decisions, is literally what I meant though.
I am a longsword, rapier, and sword&buckler HEMA fencer, so I've got literal hands-on experience with those weapons.
Arming swords weigh like 800g (that's under 2lbs). Longswords (125-135cm length) weigh ~1,5kg (a bit over 3lbs).
They use leverage and the kinetic chain of the body. Big muscles help, sure. But they don't bypass skill.
Earlier today, it so happens, I almost got my ass handed to me in longsword by a petite woman. Sure, i can use my physique to force the bind and blow through with an opponent like that, but if she reacts fast, she can simply let my blade go past and Schnappen/Colpi Di Villano me in another opening. Or just use a beating to slap my weapon offline and hit me. Or use leverage on the weak of my blade in a bind. Etc. etc. It's a mind game, just as much. Physical strength only gets you so far.
Also oly fencing weapons can easily kill if sharp, an epee is basically a smallsword which was
super deadly. And oly fencers can
destroy most HEMA fighters (using historical weapons like sword/rapier obviously) thanks to their speed, too. What use are the muscles if you've already been poked through?