Here's the point. I'm very familiar with fencing up until about a decade ago, about as familiar as you could be. I had to be, it's where I earned my living. Nobody talked about the Spanish because they weren't even on the map then. The revitalization of the Spanish school is very recent. No, the world may not be limited by my familiarity, but the fencing world is fairly narrow, so it's not hard to be that familiar with it all. Just look at the history of fencing, you won't find much mention of the Spanish school in the last century. Don't make me dust off my Thimm to cite some dates...

Let's look at boxing again. Imagine somebody wanted to use a technique forbidden by modern rules, like say 'elbows'. Of course, the international boxing world would disavow them because it wasn't boxing, so this elbow school did it's own open tournaments and called it elbonian boxing. Let's say be generous and say there are a 1000 people who participate in elbonian boxing. These elbonian boxers never manage to secure any significant wins in any international competition. How do you think the boxing world will react? They'd say "Why should we play this new elbonian boxing game? Why can't you guys play the original game? Is your style to weak to stand up in the normal game?"

The fencing world is much older than the boxing world. We have internationally accepted rules, internationally recognized certification programs for instructors, provosts and masters, and a worldwide following. In short, we are very well established in the world. Can you call your new game something else? SCA or something? Fencing is neatly defined. The whole use of the term "modern fencing' is a bit silly. There's fencing. Then there's people who do stuff with fencing swords. Just like there's boxing and people who do stuff with boxing gloves.

Plus you really lost me here -
They hold open tournaments which don't forbid modern techniques and which modern trained fencers can (and do) join. This seems like the modern guys doing the excluding.
- If some 'modern' fencers are joining, who's doing the excluding?