Coloured "dog-ears" at cards chosen freely - like Archidekt does

Please add the option to “tag” or “highlight” individual cards (similar to a bookmark or dog-ears in books), perhaps using different colors, much like Archidekt already does. That’s really the only thing that puts Moxfield at a disadvantage compared to the aforementioned competitor site. And before telling me that the “highlighter” feature already exists, it only highlights certain cards that meet THE SAME requirement—whereas what I mean is being able to highlight (and thus isolate, perhaps with different colors based on the meaning I assign to each one) INDIVIDUAL cards as I please, at my discretion, and according to my intent.
For example, I can select and highlight the cards in my deck that I’m unsure whether to keep or remove, or use them like custom tags—but much, much faster.
I think that’s really the feature that’s missing, and I’m certain of it because so many people feel the same way I do, and I’m sure they’d implement it superbly because Moxfield is top-notch when it comes to the graphical UI.