Given a single opponent, there's no way they can grapple, smash or step off line once right of way is established unless the swordsman can't hold the line. Step in to grapple or smash and you get stabbed. Step off line and the line moves with you.

The notion of the strip being limited is a bit deceiving. Sure, fencing is fought on a strip, but there is room for side stepping. In fact, it's a classical move. You really don't need that mush side stepping when your using swords because of the line. That's a side effect of having a yard of steel. Even kendo, which is fencing in a ring, is fairly linear at the point of engagement.

The only real criticism you can level against fencing and 'real' combat is that of multiple opponents. But you can level that against grapplers too. Let me tell you from street experience, working with the clinic and such - if it's two against one and that one tries to grapple, that one is done. But then again, that's the duel nature of any combat sport. You can't really do multiple combat safely as a sport (wresling battle royales do not count ). Imagine multiple combatant boxing. Actually, there is a way to do multiple combatant fencing in western fencing and kendo, but it's a bit surreal. That's the nature of the duel - why, by definition, we use the word "duel."