Rilla sums up why interrupts are a necessity right there, if someone carries out a ludicrous attack your system means exploiting it is impossible, because everything that is planned is carried out. By the same logic you might as well make defending banned, as someone avoiding or defending your attack is an interrupt, you're cutting through what they say should happen with your actions the moment you do anything other than get hit. Playing this game without interrupts would be ridiculous, and though some interrupts are also ridiculous and can be utilized as a get out of jail free card by some people (I use interrupts a lot, though I don't think I've pushed it to ludicrous levels often or at all) they are still one of the core mechanics of post by post fighting.

Frankly, if you're worried about a continuous timeline a better rule would be to limit the amount of actions allowed in one post, in its most extreme format T1 Eden does this nicely, people aren't really supposed to launch attacks and run around and launch more attacks in a single post, it's action, reaction, action, reaction. If you're keeping your character's actions nice and concise no interrupt is going to cut out paragraphs of action.