Reading that article, I can't help but think most of those problems would be a lot less likely to occur if your cat was allowed outside with a cat flap or similar.
If you're cat goes outside you tend not to need scratching posts and litter trays for starters.
Although I'm with you on the litter tray, my poor sofa is a testament to the fact having a cat flap is no prevention strategy! I think my cat honestly just preferred scratching the couch to anything else available...
You know that cats bury their poop, right? When I lived in London, where it's the norm to let your cat out, I never encountered any cat poo in my garden, and we had around half a dozen local cats.
Where exactly are they going to bury it in the middle of a city? They're not capable of digging up concrete, lawns, hard-packed dirt, etc. So they're either crapping in the open, or they're digging up somebody's garden, neither of which is appropriate.
Unless you're literally living on a farm, the world is not your pet's latrine. Give them somewhere to do their business and/or clean up after them.
If you're cat goes outside you tend not to need scratching posts and litter trays for starters.