That's why I like VPS setups. You hit the monthly maximum, and it just stops working.
I host demos, not running a business, so it's less of an issue to get interrupted. Better an interruption than a $50,000 bill for forgetting to shut off a test database from last Wednesday.
Unless a startup has five+ nines service contracts with their customers already, a little bit of downtime once in a while is not the end of the world the cloud services want us to believe.
That's not comparable. With a VPS there is no monthly maximum, just a max load on a second by second basis. You can be hit with traffic of which 90% bounces because your server is down, get nowhere near your intended monthly maximum, and then the rest of the month is quiet.
You seem to be describing this as a bad thing instead of the objectively good thing that it is.
The ideal is obviously smoothed limits, such that you can absorb a big traffic spike if it still fits within your budget. Nobody seems to offer that.
How would you predict the smooth curve ahead of time?