Oh yeh, look at Royce Gracie got destroyed by Matt Huges over 10 years ago. it was pitiful.What's worse is that it isn't something you can dedicate a class or two towards and call it a wrap. You need to spend time both learning it, and defending against it. The technique is THAT devastating to stand up fighting.
Further, the DLT has evolved with grappling and fighting in general, so those sloppy DLTs from the 90s are nothing compared to the crisp combination leg attacks I'm currently seeing in MMA and competitive grappling.
In the modern days with videos to study, MA is moving at warp speed. Anyone that doesn't evolve along will be destroyed.