I have always found this a ridiculous request. You might block a few automated scripts, but not the majority.
I've always taken a look at most of these crawler/bot scripts that do harm, and they either a) test anyway, regardless of version, b) use other unique attributes in unique files.
for example, you can remove it in vb from footer, but the .js will still have it, so does the .css output in the source code, etc.