I don't know about refuse to use.... more like certain better combinations I have a million things that I would rather be doing.

*This is all based on the original mechanics, not DoS.
1) Anything without a Fighter. Yes, I know it is doable, but so is smashing my head through the drywall.

2) Anything with more than one 'carry' character. I define carry characters in FF1 as Thieves and Black Mages.