This is not the case. See this link: https://www.rspca.org.uk/adviceandwelfare/pets/cats/environment/indoors

Quote:

"Cats with outdoor access benefit from more opportunities to exhibit natural behaviours like climbing, exploring, roaming their territory and communicating with other cats in the area.

Keeping your cat as a house cat will help keep them away from busy roads, but some indoor environments can become predictable and boring, leading to stress, inactivity and obesity.

It can be particularly hard for cats to cope with living indoors if they have lots of energy, love to explore and have previously been allowed time outdoors.

However for some cats, for example those with a disability or medical problem, living indoors could be a better option, and they may feel more comfortable. "

​

It may well be the case that in your country it makes sense for the local wildlife. But I don't think it's right. They get so bored and are desperate to explore, even if you play with them regularly.