>>Right, So you have no means of telling the difference between spam/porn
and a genuine attempt to provide some useful additional information
That is correct. They do not have, nor do they intend to hire, the thousands of staff members that would be required to manually read every comment made and check every link posted to verify where it's leading and whether or not it's relevant to the video. The simpler approach: block them altogether. The "good guys" always pay for the actions of the "bad guys." (And what your email provider does bears no relation whatever to video comment sections on YouTube.
Your other rants on other topics can be reserved for elsewhere. I have plenty of my own, but I'm entirely aware that Google doesn't give a flying rat's ass what I think, so I don't bother.