First, thank you for checking my changeset and reverting the mistake I made. I should have been more careful, you're right.

Second, according the Crossings page on the wiki https://wiki.openstreetmap.org/wiki/Crossings (which is the reference, as far as I know), it seems that even if redundant, using "crossing=marked" is the correct way to tag it, if we consider the latest proposal.
Moreover, it seems that the way iD should tag crossing has not been determined yet (https://github.com/openstreetmap/id-tagging-schema/issues/408) and thus is not "outdated".
I assume that if you make such comment about the way others are tagging crossings, you have references or clear and generally admitted instructions about how to tag them. In this case, could you share them with others and edit the wiki accordingly?

Third, while reviews, discussions and suggestions for improvements are welcome, there is no need to be aggressive or unpleasant. Such behavior is not constructive and repellant. You could have written your comment in a kind and caring way. One could not improve and would no longer contribute if they are being told off.