Here in the UK it's certainly possible. We call it stoozing.
The basic steps are
I guess people get away with this because the number of people with the skills/diligance to do it right and who can be bothered with the hassle is fairly small.
It's still possible, but current money market and other guaranteed rates are so low that it's usually not worth the time and energy. However, even if interest rates were higher and it possibly would be worth it, it's not something that credit card companies worry about. They don't care if you're making money on the side. All they care about is that they make a profit. They make a profit on every purchase you make with that card, and on any future interest you might pay if you don't pay it off in full.
Not long ago my wife received a credit card offer that was 0% interest for 12 months with a 0% balance transfer fee. I did a double take but confirmed it to be true. But still, we tossed it in the trash with the rest of them because it wasn't worth our time...
Update: Just received another balance transfer offer for 0% for 14 months, with 0% fee. Here's a picture of it since it's kind of hard to believe:
For many years, any balance transfers cost between 3 and 5 % one-time fee, in addition to the interest, which is often advertized in large letters to be 0%.
It is typically in the fine print, so you might miss it, but there are no offers without it.
So no, it is not possible.