Most mIRC websites would ask you for the source code, not encrypted code, anyway, Just like they do with DLL's.

Which would make this 'compiling' usesless for mass distribution. Nobody would choose to download an encrypted one over a normal one, There would be no speed advantage, Infact the encrytped one would take longer to load. It's not as if you can compile a mIRC script to machine code. It would just be trivial encryption - for the purupose of making it unreadable. That isn't the purpose of compiling in any other langauge.

And for personal distribution, You should be able to trust people enough not to rip your code...
If someone wanted to send me a script, I would never accept an encrypted one, when they could just as easily send me a plain text..