“!” means NOT so when you drop p2p=!all-p2p you drop everything else except p2p (what the internal MT filters consider “p2p” which could include non file swapping stuff ? )
so if you want to try and drop “p2p” remove the “!” from the “drop” rule.
But nowadays the file sharing soft has protocol encryption so users will still be able to use file sharing programs like uTorrent etc.