The user doesn’t “have to remember” anything. They just have to click on unknown words in any text to get a definition and to mark those words as unknown, as described in the knowledge base here: Vocabulary / SRS Review.
I mean, it’s what they’re doing anyway. It’s hardly rocket science.
And life is full of disappointments, major and minor. Most adults are mature enough to take tiny inconsequential disappointments like this in their stride, and are able to refrain from cutting their nose off to spite their face by ditching one of the best language-learning tools in existence.
If they can’t take such disappointments, maybe they should hide themselves away in their parents’ basement and not expose themselves to this awful world we live in where… checks notes… language learning software developers expect users to use their software as it was designed to be used, and as is clearly explained in the app’s knowledge base.
And the accusation that LingQ is “changing one’s data behind one’s back” is complete nonsense, unless you’re the kind of person who turns his back to the computer while he’s paging forward.
And if it damages a user’s streak, it’s almost certainly going to happen when the user is brand new to the system - on day one. It’s hardly going to happen on day 150 of a streak, now is it - I mean unless the user is completely stupid or clumsy with his/her mouse clicks.