It's not that there can't be real effect, it's that they aren't LAW. If people go along with it, they're getting a sort of pass that says "hey, this is illegal, but we won't prosecute you". That's different than it being an actual law. The outcome is essentially decided by the people capitulating to these stupid things. This is why Harvard, GW, Stanford...etc are taking this court, because they know they will win on the LAW.
Judges can't use EO as law. Fact. If Trump tries to influence the public at large with these stupid things, it will AND HAS get shot down in court.