Socketed items are already locked though if you manually use the crystal. Locking items as simple as placing calcite or equipping said item. That's why most wouldn't be sold with sell all.
I mean if it's a item that isn't legend, it won't be auto locked but you can at least wear it or place calcite and lock it manually. Then sell all and done. Your locked items ofc survive.
Oh and btw speaking of locked items, I remember in the old days when you could unlock legends and sell all lol. I miss that feature tbh but that's ok. Or maybe it wasn't like that. I don't remember too well though.
If you could do salvage all or sell all on legends though , that could be nice but at the same time, I don't mind the current system as legend items and crafted items safe from the sell all (including the item with just calcite on epic or below rarity items).