It's not like there seems to be bountiful examples from play of single classed fighters. I mean, years ago, I posted a poll that got some response:
https://www.enworld.org/threads/pol...-levels-in-a-class.592445/page-4#post-7255673 - and only a quarter (although to be fair, it was the largest single group) of characters had 4 or more levels in fighter. Hardly scientific, absolutely.
But, my experience mirror's
@OldSchoolGamerGirl pretty closely. Fighters, as far as any of the groups I've played or DM'd for, might as well not exist.
Then again, I don't see halflings either.