This is El Capitan. On average 2-3 people die climbing it every year.
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There is no way from the base of the cliff that you can tell if there are handholds for any particular route up this from the base. You simply won't be able to see enough detail. The first woman to free climb it in history was in 2020. It is an incredibly difficult climb. There are worse of course, cliffs no one has ever climbed. I mention this one because I've seen it up close and even in my young and stupid days there's no way I would have considered climbing this.
I don't really care though because this is not about the DC I set for this particular cliff. In D&D the default is that the DM decides the DC, the monsters, the NPCs, every tree, bush and blade of grass that is relevant to the game. I set the DC at what makes sense to me. Making accusations and nit-picking things you obviously do not understand does not change that. You may not like the base assumptions of D&D, I do.