No one cares if you or someone else uploads this, just that the quality is good. It's not like you are the artist.
Of course someone cares: The person who didn't get the upload and wasted their time for tagging. One could say that Danbooru becomes a huge waste of time if other guys are sniping you or if you are constantly sniping other because the sniper is pressing F5 every second...
I usually add a fair amount of general tags before hit the upload buttons and then fully add more details tags later since review and tag it on sample page is easier than upload page. Being snipped all the time, not that matters but I do tag before upload dah, just saying :I