Why? Because they serve just about every use case and scenario. I've myself spun up $5k/day resources on accounts that did four magnitudes less / day before that. There are some limits by default which you can get raised, but they're not going to prevent a $50k bill - at best, they're here to prevent a $500k one.
Anyway I agree they could make it clearer that you have to do all this crap yourself but it makes for a poor sales pitch.