There’s a very finite amount of coastline and the Coastal Commission is charged with protecting the public resource. And they’re doing a good job. Sea walls are not in the public interest. Sea walls may be in the interest of a small, wealthy, vocal minority who owns land on the bluffs. Often the deed just says they own to the bluff, which is brilliant because the ocean can completely reclaim their land eventually.
We’re not going to stop the ocean from rising. The question is what do we choose to protect over the long run?
Today we (humanity) aren’t. If we had started to listen in the 70s that might have been a different question.
Is there no way to both slow coastal erosion and protect beaches?
Not really. The ocean is going to constantly move the loose sand on the beach around from place to place, which means, away from wherever it is right now.
Whoever builds devices to prevent new sand from coming into play, or devices to trap sand and key it from moving, will starve the downstream places that would normally receive that sand.
