I still don't get this main/only benefit of declawing.
So yeah, you haven't bought a cat-scratch-tree for your indoor cat to and/or haven't been able to teach your cat not to scratch the furniture. You probably also leave your indoor-only cat alone (=no second cat) while you work the whole day.
You're not good at keeping cats, congratulation.
But let's assume for the discussion, you have untrainable cat(s) that regularly, create a lot of damage to your stuff.
In the OP it is mentioned that this is apparently about people who are too poor to buy new furniture. First of all, are these the people who would care about some scratches on a chair? Please explain what kind of cat can render furniture literally unusable. Soft couches I guess yeah, but you could e.g. buy a couch-cover. That will also help when you spill stuff. Don't forget that a declawed cat can still bite, pee, shit and throw up.
Also, are these the people who buy some sort of expensive furniture that can't be replaced anyway?
In short, I don't get for whom declawing their cat is actually a necessity. There is a good reason why it's illegal in Europe. Basically the laws prevent any amputations (like the cosmetic stuff on dogs). Would you also recommend removing a dog's vocal cords because he's too loud. It's also necessary I guess...
If you have a pet, simply be prepared to have collateral damage. I've seen households with dogs that have doors that were almost fully perforated by scratches of said dogs (much worse that what any cat could do, not to mention dogs can't retract their claws and you often get slight unwanted damage). If you have rabbits, they will bite every single cable and other stuff in reach.
Etc. Etc.
and regarding the OP's comment about recommending cats to be indoor only: That seems to be a US thing because in Europe IMO the opinion is more like that you're a "bad" cat holder if you keep it indoors (alone). In fact, the cliche is that this is only done by old women in city apartments. At the very least you should have more than one cat or it will be bored to hell (and destroy your stuff while you're gone

).
Obviously there is a higher risk of them dying/running away, but it depends on your perspective. Do you also want to keep your kids locked in a golden cage, too? The fun part about cats as pets is that they are mostly independent. They come as they please and live their own life and make you part of it if they like you (and your food).
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I'm pretty sure different breeds of cat also have a very different temper / common characteristics. I bet there are some that generally are less playful and/or can be trained easier. (or even ones that don't have the urge to constantly sharpen their claws - which is the main drive behind scratching wooden furniture). So buy those instead.