They are compatible. That warning is from 2011-2012 when FX first came out again. the board are all up to date now. Unless you're buying from a mom and pop that has had it in inventory for years and years just gathering dust.
If you somehow get a board that isn't updated it will be a pain to flash because they usually don't post without a compatible CPU, meaning you'd have to source an older Phenom II era chip to get the flash done.
Honestly i don't think that will come up. If it does we can always help you here.