[SXX]

Huge reason was that Google also simultaneously pushed AMP while hiding that pages are hosted on Google servers. So if you visited page like:

  https://google.com/amp/something.com/directory/article

And in your address bar there will be just:

   something.com

This is literaly URL hijacking and it's fundamentslly breaks trust in your address bar.

[fastball]

Did google do that as part of this feature?

[SXX]

No, but I sure backlash against feature discussed here wouldn't be as big if Google's other hand wasn't pushing fake URLs for AMP pages.

[fomine3]

You may refer SXG, but it seems that anyway SXG overrides URL to origin. So this is irrelevant.