Sure Crono was tough. We all can see that. (Zaperking what they meant was that you could beat the game in New game + with just Crono if you accessed the portal.)
Well, I know that already, in fact, I acknowledged that. Crono is tough, and yes, overwhelming numbers would definitly defeat him, there is no question about it.
He certainly would've lost in a head on confrontation. But, while he was strong, I don't think he was stupid, and at the very least neither were the other people around him.
Lets say he can take on 20 people at the same time (fairly conservative number considering the power of Lavos and other enemies he fought... but thats opinion). Now, lets say he has the support of Marle for healing, and he pulls the other members of the travelers up, if each of them (aside from Marle and Lucca, though they could both do it with magic easily) can take on 20 people, thats at least 100 people right there just to take out the 6 of them. If we assume a reasonable battle strategy such as: don't fight 20 people with your sword alone, that number could easily go higher. Even only using basic techs the number would climb to most likely somewhere over 300 just to take them out. We really can't say, but either way:
That would be a huge morale breaker.
But there are ways to kill without openly attacking. Poisons.
And then I'll reply: Antidotes

.
And next you'll bring up magic. Well magic has its limits. There were MP points used. And while I"m not saying he was in battle and went "Damn out of points." More likely it was a representation of his own energies reaching their exhaustion point.
Who said I have to bring up magic (though I did

)?
I would definitly hope he's not literally "running out of points," though that would be very comical.
As I mentioned above, if you were in the opposing army and you saw 6 people take out over 300 people relatively easily, you would probably break and run, I know I would. Even the most battle hardened veterans would be willing to "strategically withdraw" after that. Don't forget that they'd likely be backed up by Guardia's army.
And finally I'd bring up Crono's noble nature. His willingness to sacrifice himself so quickly in Zeal against Lavos. Maybe he did something like that. The greater good.
To talk about this, I'll just paste part of a theory I posted in the "Did crono die thread" (rather than retyping it), I think its fairly solid.... well, as solid as something based completely on hypothetical events and timelines can be.
Next, lets look at a more specific possibility; ok, so this time only Crono lived, Marle is definitly dead (as she is the princess.. one would assume they would have killed her). To disprove this idea (or discourage at the very least), I invite you to picture the final scene before the fall of the castle to Poore. The poorean (sp?) army is pushing towards the castle at a rapid pace, the knights of the square table, etc. just can't hold them back any longer. It is incredibly unlikely for them to be murdering every resident on the way (only the absolute cruelest and stupidest armies did that), so the likely scenario is that, while towns are perhaps devestated, the people remain unharmed. The king orders Marle to leave the castle, contrary to some popular belief I do not believe that Marle is stupid nor a bimbo (and I don't see much evidence supporting that she is one); she leaves. This means Crono has a choice, either protect his relatively new wife and live to fight another day, or abandon her to fight a losing battle at the castle. While if it wasn't for Marle Crono would probably stay, I don't believe there is anyway he'd let her go off on her own. He leaves with her before the fall and they go into hiding.
Note that I agree with you're Crono and Marle going into hiding idea, personally I think thats the most likely outcome.
Either way, this thread isn't about whether Crono died or not, my point is that there
had to be a dimensional split at the point where you make a choice to either ram Lavos with the Epoch or fight the Outer Shell.