Because EICAR might get the email straight blocked instead of marked as spam.
If you look at what gets copied to the clipboard, GTUBE is at the end of it.
I just sent an email from my gmail to my Gsuite backed mailbox with the gtube text, didn't work :(
the email landed in my inbox.
My selfhosted mailcow (https://mailcow.email) instance blocked me from sending it (the SMTP server actually rejected it), and then blocked the one I sent from Gmail to it with 554 5.7.1 Gtube pattern. Didn't even show up in Spam.
that is pretty cool, it's like a virus hello, world!