all he means mate is that, to go online you need a dump that was done by gateway, as it has the extra data.
when omega was released, some roms were uploaded that were made with gateway (since previously, only people with special hardware could dump games)
so these dumps would work online, since they have the special data, but then people who were dumping via gateway releasing roms started to wipe the extra data to make it more like a 'proper' dump
so sure, a few games after omega came out will have the data, but not on purpose