It looks like we are not speaking about the same things.
What you are talking about are draft tournaments.
I am not speaking about tournaments.
In my case, i am speaking about a true game mode. Not just something for tournaments even if i think it could also work in this scenario.
For the rest, you have 100% the right to think it's stupid.
All i can say is, well.. Your statement is not supported by anything else than your own opinion.
Me, i can say this mode IS factually popular.
We can see it being implemented AND loved by a lot of people on other card games. Like Heartstone.
And, losing everything after a defeat, well, it's basically the core principle of every rogue like on the market.
It's really "not my idea". It's a legit mode, already implemented in a shitload of games and most players are already aware about the rules and how it works.
Players are not stupid.
They know how to read.
They understand things when you explain it to them. Specially when you have literally tons of way to explain it to the player.
And they wont be shocked if the mode is correctly built and everything tells them it's a temporary deck which will be destroy after x games or defeats.
EDIT:
Oh and for the promos. For me it's simply not a problem. Making special decks without promos is a way to deal with a semi-issue.
Sure it's a lot of works...
Probably too much to prevent something people will not really care much in reality...