Is it? If I'd sent a link to a document, they'd have the latest version and I could continue appending to it, and they'd have a version history and could even contribute to it if I permitted them.
The times have changed. It's not unreasonable to expect how people use email to have changed, ergo people sending emails full of URLs are statistically more often than not spammers.
Is it a broad stroke? Yup. But I'm willing to bet that I'm a fringe case and it prevents a ton of spam.
I deal with email at global scale, and yes, you're a fringe case. There are many billions of messages sent every day which have lots of links, and which recipients in general are interested in, and want delivered to the inbox (or promotions), rather than spam.
The times have changed. It's not unreasonable to expect how people use email to have changed, ergo people sending emails full of URLs are statistically more often than not spammers.
Is it a broad stroke? Yup. But I'm willing to bet that I'm a fringe case and it prevents a ton of spam.