@Frank-Steven **********
let's just make some points clear here.
1- Your are not in a position to decide what is legal required or not legal required.
Your entry is up to the IO decision.
So let's be clear here that holding a visa doesn't mean you have the full power to decide what they can ask
2 - DTV is considered as some special type of Tourist visa so, they can apply the terms of Tourist visa on the commers holing it
Which includes accommodation proof, fund, return ticket within the period of stay.