"Is the purpose of wiping the rim to ensure they seal properly?"

Yes and in many cases it can make all the difference between seal and no-seal. Especially with thick foods, less so with liquids.

But it is also done so that no food can get trapped on the rim and grow mold to break the seal over time. Even if the jar does seal molds can still develop if food is left there.

So sounds like you lucked out this time but you may find you have a shorter shelf storage life. So I'd mark the lids on these and check them carefully when opening the jars. If you then discover one with a weak seal or if the brine has turned cloudy just toss it.

Dave