Perhaps true (honestly, I'm just really sceptical about this topic) but if you're getting the item first then there's not going to be a problem in my opinion. But I find that loads of YouTubers use giveaways to try and get a higher subscriber count, viewcount or many others for advertisements and a lot of them being fakes one way or another.
For instance, an ex-friend of a good friend of mine gave away a Minecon cape (cosmetic item for Minecraft) but it found out that he faked it and gave it to a random commenter, who so happened to be the original poster's friend. He had over 1000 subscribers then, and he still does.
Unfortunately I just don't trust a lot of people unless they're personal friends. Especially YouTubers that happen to be giving away items.