Higlight coins I have/don't have in other's collection?

I know collection isn't a competition, but a fun hobby, which may contain a sprinkle of friendly rivalry.
I just got an idea, which may be controversial, but when looking thruge other peoples collections, you could have a checkbox to highlight either coins you have in your collection too, or those not in your collection, or just those in your swaplist too.

In this way one can easily compare collections and more easy/quickly see what other miss in their collection; thereby being more easy too figure out if they are a potential swap partner, for what they may miss.

I know some people prefer to keep their collection privat and this can be more discouraging to some, but this is an idea I had and wanted to know what other think.

Hope this make sense.
What do people think of the idea?

Best
- Jamtrup