Browsers tend to not automatically open new tabs though, but only if you explicitly do something to cause it.

Maybe many people do not use multiple tabs within one site/app, and that doesn't translate (There's probably some research out there on how people use browsers in practice)

Your app might look and feel too different from a browser or other tabbed environment. Does it clearly communicate where a new tab is opened, that you can't go back on it, ...?

I'm thinking this may be the crux of the problem. I figured since G Suite did it, it would be common enough and fine, but maybe not.

There's probably some research out there

Everything I found was about how some people never close tabs and how to deal with hundreds of open tabs. This is also part of what led to me assume that people are comfortable with the concept of tabs.

look and feel too different from a browser or other tabbed environment. Does it clearly communicate where a new tab is opened

I'm personally biased towards this answer. Maybe it works for G Suite because people understand "documents" as being self-contained in separate screens and that does not intuitively carry over to other things. Leveraging browser tabs is so powerful and useful, so I'm hoping some extra communication effort will solve it.

Don’t matter. Listen to your users. Try not to argue with them. Good luck.

At the end of the day, I will absolutely listen to our users (and definitely not argue with them). Always a great reminder, though, thank you!