Worth separating two things that keep getting welded together in these threads, because Servury is a clean example of the difference and people are about to learn it the expensive way.
Fast provisioning is an operational property
Ninety seconds to a box changes how you design, not how exposed you are. It means infrastructure becomes disposable: you stop repairing things and start replacing them, you stop caring about a box's history, and the correct response to almost any incident becomes "burn it and rebuild". That is genuinely valuable and it is available from plenty of hosts who will also cheerfully take your passport.
The corollary nobody plans for is that disposable infrastructure requires a rebuild script that actually works, tested, in a repo that is not on the box. Without that you have not bought disposability, you have bought a faster way to lose things.
No account is a privacy property with an operational cost
The cost is recovery. There is no password reset, no billing history to point at, no agent who can be persuaded that you are you, because from their side there is no you. If you lose the key material, the box is gone and there is no argument available to you. That is the same trade the API-only hosts make and it is a fine trade, but it has to be a decision rather than a surprise.
Where I would put the line
Under a month of intended life and nothing on it you would miss: excellent, and four dollars is not a typo. Over three months, or anything with state that matters: I want a provider whose worst week I have already read about somewhere, and a newer shop by definition has not had one in public yet. That is not a criticism of Servury, it is a criticism of buying anything important from anyone with a short public record.
I have not tested their cash-by-mail path, so I cannot tell you whether it behaves as well as the coin path.
Summary: brilliant for things you plan to throw away, and the plan to throw them away is not optional.