As with anything, the answer to this question is context-dependent. The only time questions like this would ever be black and white is if everyone was literally the same person—Same weight, height, genetics, food intake, activity, etc.
No matter where you fall in the following scenarios, the reality is, while for some people home workouts will be more effective than for others, doing something is much better than doing nothing at all.
So, let's quickly break down the effectiveness of home workouts by looking at a couple of scenarios:
Scenario A: If you're a person who generally stays active, trains with moderate intensity 3-4 times per week, and you don't have specific goal you're charging towards, my answer would lean towards yes, home workouts will be effective for you.
The questions you're asking yourself about the factors you're measuring to determine "effectiveness" are unique to you, but probably go something like:
Have I moved my body (exercised) for 30 minutes today?
Did I work up a sweat?
Did I overcome an internal conversation to get moving; keeping me mentally sharp?
However...
Scenario B: If you're a person who is very committed, trains intensely 4-6 times per week, and you have a specific goal locked in...the effectiveness of a home workout may just not be fully there. Why? Like above, the factors you're measuring are simply different.
So, let's say you're a powerlifter (picked this because it's easy). In simple terms, a powerlifter is only focused on moving A LOT of weight from point A to point B. That's it.
A powerlifter training in accordance with modern programming backed by science (following some form of periodization) will ask a question like:
Have I completed my scheduled 4 sets of deadlifts today at 72.5% of my one-rep-maximum weight?
I'll stop right there because, if you don't have a home gym (99% of us do not), the answer will be no, your home workout will not be as effective for you. As much as I believe in home training, the results from deadlifting a jug of water 200 times will simply not assist you in moving progressively heavier weight from point A to point B. Not effectively, at least.
