We need to make a distinction between how the church arrived at certain ideas and the value of those ideas now in their mature state. Otherwise, we fall for a genetic fallacy. Like if someone said that Luther discovered righteousness by faith while climbing pilate’s staircase on his knees, so there must be some importance to that ridiculous ritual.
It makes no difference that some guy came up with the sanctuary idea while walking through a cornfield, that EGW couldn’t understand anything going on at the Bible conferences until God took over and helped her guide things when people were stuck, or, that EGW continued to endorse 1844 the rest of her ministry.
Today, we’ve had these theological elements for a century and a half with plenty of time to develop them and understand what they are about so we need to judge them on their own merits in the context of the wider Christian theological landscape. And, when doing this, SDA theology has no need for EGW but can stand just fine on it’s own feet.