Okay so to do that, I need to be a rank 6 blacksmith. No problem, went and leveled that up. Okay, so where do I get the supplies to make the sword? Well, I need to make a blade that requires me to be a rank 11 blacksmith to make. How does that make sense?
Just a thought, but let's say you decided to take up something like sewing/tailoring in RL. Would you immediately start out by carving buttons, sewing cloth from thread, smelting metal for clasps, etc, or would you go and buy the things you don't have the experience yet to make?
Modifying and putting things you bought together is much
easier than making every little thing that really goes into a creation.
That is how it makes sense that you need to be higher level. What would you as a person think would be more complicated for you to do: binding a blade to a hilt or creating a blade from raw metals?
It sucks in game, but it makes perfect sense if you think about it.
Here's the thing - realistic does not mean fun, and it does not mean good game design.
And it undermines your case that the crafting system is realistic and this is good when you make as many mistakes describing the process as you did above.
For example, one does not sew thread into cloth - it is woven. And this is something that it done by weavers, not tailors, which in real life are completely separate professions utilizing unrelated skills.
Tailors don't make buttons - that's not even part of their skill set - woodworkers and bone carvers make them. The same goes for clasps, which would be made by metalworkers. None of that is a matter of experience - no amount of skill as a tailor would allow you to make those things in real life.
Similarly, one does not "bind a blade to a hilt" - the hilt is an accessory, and it is mounted on the blade, or more precisely to the tang. And mounting the blade's accessories isn't part of a blacksmith's skill set; it's not part of any profession's skill set actually, because it's so ridiculously easy to do a trained monkey could do it - it's the kind of thing the end user is expected to be able to do.
And the realism argument is pretty much completely negated anyway by the fact that in real life, I don't need to be a better tailor to mend cotton than to mend hemp.