despite what people say at least mediafire can keep files up for a long time, but its riddled with ads anymore
adblock/ublock is great but not everyone has one or cares to get one - i almost had to restart my computer because of the ads invaded my screen and couldn't close it
yes dropbox is stuff avoid using it - they randomly prevent people from sharing for no absolute reason - if you get lucky you may never get blocked from sharing files, but a lot of people are getting blocked from sharing files in general