Not true at all. Before the EP, slaves were taken as "contraband" or accepted as refugees if they could get to Union lines, but if the owners could get into court the courts would order the "property" returned if owner could demonstrate that the slaves were not providing direct support for the revolution. Without the EP, at the end of the war, owners would be able under the law to reclaim their property. The EP changed that and designated any slave residing in rebelious territory as being automatically a material aid to the enemy and declared them free for all time.
Yes, the EP was a political statement, and a powerful one, but it also had significant real results in permantly freeing millions of slaves.