It's because of the market
when you put same price with another seller on the market the one that decide your card is the first one is the name
0 is the first letter 0-9 after that a-z
if I'm not wrong, there is another one before 0, which is symbol for example: "-" example: -tanto89-
someone sell jeyn at 240
1. Buy - 7 4 max - 238 Clintz sold by XXX, 68h, 16min left.
you want to sell jeyn at 240 too
but you want at the first row (if someone wants to buy a card, they will buy the first one right?)
if you put your name 0 in front of your real nickname:
it will become:
1. Buy - 7 4 max - 238 Clintz sold by 0-tanto89, 70h, 00min left.
2. Buy - 7 4 max - 238 Clintz sold by XXX, 68h, 16min left.
got what I mean?
or alternatively, you can put 1 clintz below the cheapest seller
for example, they sell jeyn at 240, you can sell it at 239
It's actually a remenant of a very old DT system
in the old rooms there was no random matchup system and it didnt order you randomly in the room.
a 0 would put you at the top of the list, meaning you would get more matches as people usually dont want to scroll down too much
And one more reason is the same reason that I have a dash in my name (well, other than ascetics, which I know I spelled wrong): The name is taken. Yeah, I'd like to have Argos as my actual name, but some player who got to level 14 and quit took that from me.