Surely Samsung are just covering their arse against people misusing batteries and blaming the manufacturer. The battery doesn't know what it's being used for and a vape doesn't do anything unusual electrically.
If a battery is safe up to a particular sustained Amps draw, then it doesn't matter whether it's powering a laser cannon or a doorbell, as long as you don't exceed that Amps limit.
I have many different types of batteries with all sorts of ratings, including Samsungs rated at 30A. I have used them right up to the limit with no issues. I have also used Efans rated at 31A which exceeded my personal temperature limit after six seconds at 22A, so the question is not whether the battery is specifically designed for a particular application - does the battery in your TV remote say "Designed for use with your TV remote"? I don't think so - it's whether you trust the manufacturer's (or re-wrapper's) claims.
Here's what I think the people at Samsung are probably thinking: They know that some vapers are using their 30A batteries in mech mods at resistances as low as 0.14Ohm and getting away with it, so there's a danger some people might think "Aha, Samsungs are good for thirty Amps" and assume that all Samsung batteries are capable of that. The warning is thus to protect themselves against accusations from people who don't read and/or understand the small print.