It's also expensive - time/efficiency wise.
Currently, most mods that look for chat commands, including ULX, look for JUST one character in the very first part of the string.
If not there, continue/do nothing. No table checking needed for majority of what all the players say.
Once you start trying to monitor EVERY chat to look for those keywords, on a busy/chatty server, you're going to see lag after each person says something while it loops through the table on the first word.