OK - I see your point. I feel to that today's modern in-line MLs aren't much less than a single shot centerfire rifle. The accuracy and range of them was unimaginable 25 or so years ago.
While I have no grudge against anyone using them, there is something to be said about using a flintlock and a PRB and having to "get in close" (closer than a modern scoped in-line) that provides an additional challenge.