Quick chem question????

okay so lets say you have ethanol and methanol and you want to synthesize ethyl methyl ether. i know you have to do williamson ether synthesis and i understand how to do that using like sodium metal blah blah blah....but why cant you just mix the two together and add acid and heat...is it because of the formation of water or because the acid/base reaction will occur faster than the sn2 reaction?