Typical mentality of an ignorant, narrow-minded meathead.
Sure a little narrow minded but here's the rub:
1. Home workout programs almost always have issues due to the limited equipment. The hamstrings and lower back for example are usually underworked, as are the traps. There are ways to do it but they are so inferior to the equipment available at a gym that it's kind of silly not to go.
2. Much of the 'sell' behind beach body programs and most fitness programs relies on the idea of muscle confusion. Muscle confusion doesn't work. The whole point is to perform an exercise and increase the intensity over time; switching it up every couple of weeks puts you back into a neural retraining period where you're being submaximally worked, and more effective exercises are regularly subbed out for worse ones for variety.
3. Everyone thinks that whatever fitness program they did is just the best because it is both the first time they've ever really exercised hard and consistently and their body is very unfit to start. The programming could be pretty crap and they'd still get very good gains... For a while.
4. These programs encourage the use of expensive proprietary nutritional supplements and their dietary advice is so-so. There is a clear conflict of interest where they are advantaged by you buying their crap.
They have advantages:
1. They make you exercise hard. A lot of people will slack or not be consistent if they don't have the videos and the schedule.
2. They allow people with zero knowledge and no willingness to learn to get in better shape, even if it's suboptimal.
3. It's a well presented package and entertaining, and the best program is one that you'll actually do.
So even if someone is usually better off getting strong at the barbell lifts in a systematic and progressive way, layering in some conditioning and ancillary exercises later in to round things out, and eating a sensible diet, some people just won't do it and p90x beats the treadmill. Same thing with crossfit. For those people this service is very useful.