Everybody can quickly google a few articles of questionable quality to suit his opinion.
Keeping cats indoors prevents them from hunting, roaming, marking and patrolling their territory, exploring and climbing. Indoor cats often suffer from extreme boredom, hence why they keep attacking your indoor furniture. Indoor cats are also more likely to suffer form
abnormal behavior:
Indoor cats are also more likely to suffer from
obesity and diabetes.
Indoor cats also suffer from a wide range of disease that war much
less prevalent in outdoor cats:
Here is
another study coming to the same conclusions:
Here's another:
Anxiety and scratching of furniture are also way
more common for cats who are being kept indoors.
Cats scratching your furniture is most likely a sing of bad feline care, too many cats in a single household or insufficient environmental stimuli. I never had a problem with cats scratching and destroying my furniture or my TV.
Lastly, indoor cats seems to be
an American thing, because here in Europe it is very frowned upon. For example, You will not get a cat from an animal shelter if you're unwilling to let them outside (except in the rare cases that the cat has been raised as an indoor cat by their previous owner).
In essence, you want to save your precious furniture? Let your cats go outside!