An old, rehashed and long since debunked argument. Top guilds often are forced to raid without most add-ons, as things like data for DMB simply do not exist for them yet while many other add-ons are simply too dysfunctional after major patch. After all, they're pushing world firsts and are people who are gathering this data for add-on makers among other things.
That and the fact that blizzard itself hosts events where top guilds clear hardest raiding content on vanilla installation live. So your entire argument is based on false premise which has been longed debunked.