[jasode]

>, but why do I have to provide my email address to read the full report PDF?

... because the people who made the PDF content want to make a trade: your email address for their PDF whitepaper.

The industry jargon for this technique is "inbound marketing".[1]

>Is this a viable strategy?

Yes, it often is. But I do get that it annoys a lot of people. That's why 99.9% of the time, I also don't bother giving my email address just to read pdf whitepapers.

It's a voluntary trade -- and like you, I usually choose not to do it.

[1] https://www.google.com/search?q=%22inbound+marketing%22