Most fantasy knight don't have magic.
Said as if anyone had done a comprehensive survey of fantasy fiction to determine this.
That's the whole problem.
With respect, that's reductive to the point of being un-actionable. Having seen so many of these arguments over the decades (yes, decades - this is an old axe grinding here), there are many aspects to the "problem", and that knights in fiction don't use magic is only one piece of it.
Until you are willing to accept that, so long as you go forward with this over-simplified problem statement, you will get precisely nowhere.
If perpetually arguing (remember - decades) is sufficient, then this reduction is a reasonable choice. If not, the reductive approach is highly flawed.
People wanted a class feature or class archetype to make up for boosting Cha or Int or Wis over Con or Dex for your nonmagical warrior.
Oh, "people" have wanted far more than that. There's 40 pages here, and again decades of argument before. It isn't all over one class feature.