Contrary to the downvotes on the above comment I see absolutely zero issue with wanting to be informed of this in advance. I would've made this exact same comment if I had run into it myself.
After you click the button to try it...
...
I have the same thing for articles where I click on the submission title and there's a paywall. I want to know about the wall before I get there so that I'll know it's not worth the effort. Usually this is achieved by looking in the comments for an archive link so in that case I don't care about there not being a warning in the submission title because the comments allow me to enjoy the content anyway. In this case there's no need for a warning in the submission title because I go to the website and I get a neat idea, that's fine, no wall yet. There's a button to try it and that's where the warning should be that a Google account is required. Your argument is what's ridiculous.
See my other comment: https://news.ycombinator.com/item?id=42407232
As an example: I recently bought a piece of software for my new Mac that I had good experience with some years ago, only to find that it's not compatible with the newer models. Upon contacting support about it, this is a known issue with a whole support article written about it. However, it wasn't mentioned anywhere on the landing page or buy pages. They're working on a beta that will warn you (still after you've already installed the software) if it's not compatible with your machine, but again... if I had known this I would not have purchased in the first place. I feel tricked, and upset. This is the same type of feeling.