Its true. But there are also a lot of downsides to home gyms.
1) You may not have the money to purchase everything at once.
2) You may not have the equipment you need for certain movements.
3) You may not have the space for all your equipment
4) The atmosphere of a home gym and a commercial gym are different. Some people enjoy the change and most people enjoy leaving the house.
5) Unless your wife/girlfriend/roommate is willing to spot you then you're on your own for lifting which means taking extra precaution before doing certain movements (bench press mostly)
But depending on your lifestyle, a home gym is the best option. Personally, I prefer my home gym for time and hygiene purposes. I have a squat/bench rack and adjustable bench with ~400lbs in bumper plates, a door way pullup bar, an abmat, abwheel, and a few other odds and ends. Otherwise, I have everything I need. I REALLY want a pair of the Bowflex adjustable 90lb dumbbells - but fuck you for $600.00.