This can apply equally to any traditional martial art, not just Karate.

Have you ever demonstrated a way to protect yourself (or seen somebody else do so), only to have somebody else say, “but that’s not really Karate”, (or whatever martial art you practice).  This can be particularly true when styles that are considered primarily striking arts (like Karate, Taekwondo, Kung Fu, etc) start using grappling applications like throws, locks, restraints, escapes and the likes.  People can be quick to pigeon-hole what they consider to be part of a martial art or not to be part of it.

Are they right to do so?  Does this keep a martial art ‘pure’, so that they don’t all just merge into each other?

I’m sorry to say, but that kind of thinking is really missing the point.  Originally, the martial arts were to protect the practitioners life; so can you imagine somebody back then saying something like, “I’m not using that technique as it’s not from my style”!  Of course they wouldn’t; they’d absorb anything that might save their lives. Read more