Well, these days sure. There are all sorts of blends of styles being taught around the world, including flavours of MT. When I say pure MT I mean the MT that has been generationally taught in thailand. Originally they didn't use closed fist punching at all but rather open hand slapping. It wasn't until the 1900s that western boxing began to creep it's way into the syllabus. Even today, many traditional MT guys keep a very rigid upper body.
This was more of a response to your claim that kickboxers punch softer than boxers due to mechanics, and that is not strictly true.