It's questionable (although certainly possible) whether ColdFusion's custom tags inspired custom tags in other languages. There were a lot of other elements in the air at the time, such as server side include syntax, that made the idea of incorporating programming logic into markup a logic next step. And then from there it isn't too far to get to custom tags, of course, it's hard to retrospectively estimate the amount of brain effort to leap between concepts, so maybe my assessment is way off, but this is where finding direct documentary links between how technology developed can be helpful.