I actually think it does, if you think about it. Gellis is a *woman* in the 18th century. She can't just caper about wherever she wants to go. As (I think realistically) shown in the books, women were pretty in danger of rape or other violence when travelling alone. She, like Clare, had to come up with a realistic story about where she was from, why she had no family, etc, and basically find a group or man to protect her. She found a man to marry her with NO evidence of who she was or where she came from, and was probably supremely lucky to do so, rather than ending up in a whorehouse. Upper-class society would be HIGHLY suspicious of a person of no known family, and it's not like she could easily swing from man to man once she got an established position. It's mentioned in the book that she wanted to get to Colum (persumably to get the Mackenzies fully engaged in the rebellion, and perhaps use his influence to get more clans involved), but had to settle for Dougal. Just because she's a fanatic, doesn't mean she is an expert at how to change history -- she just thinks more Scots should have rebelled. As we saw with Clare and Jamie, it's not so easy for an average person to chance history.