Okay, I see my friends are here to talk again...
Just as an information he can't forbid multiclient. There are alot of ways to do multiclient like sandbox or a virtual machine like in the good old times (tw). He can't also check for ip because two different people in the same house have the same ip.
Why he cant? (btw. who is this "HE"?!) And ofc he could. He could make a rule against it. After that, good (and with honor!) players like me would report all these (most time) clanless majins. Normaly the stay in citys or Q checkpoints, rly ez to find.
Anyway interesting that you talk about sandbox or virtual machine options 
Yo , i will explain u why we need that multi account to grind in this game " correctly " u need and alt buffer or healer or poko . + a AOE damage char or a tank ..
Grinding is by far the best solution to make zenie's (at least for mee ) cuz u can get items / stones / sell to marchands ... give mee one just one answer to this question , why auto pot's shouldn't bee an ugly item ? all classe's should have auto popo's ..
i'am an actif player i made my poko 3 days after OB started i'am online like at least 6 h day i still need one z24 how is this even possible ?
note : all tokens i got have gone in z24
You don't have to...dude
I see the reasons why you have to. But I said already to another thread: If THAT would be a option by the devs....
Why it isnt possible to play 2 chars with 1 account?
Why are no "mass buffer" NPCs at every point?
Why is every class not able to buff himself as powerful?
no need to explain it to him basically that been told long time ago and he still against it soo yeah let him enjoy a game where multi clients is possible :V
Long time ago? A month ago...what a long time 
And I still wait 4 your arguments. But this time, I just give you just one: Call me ONE! succesful mmorpg where multiaccount is allowed?! 
Anyway, back to the topic:
My real problem is - all these casual votes!
We have already more DB Hunt days!
We get super armor or better from NORMAL mobs!
Now this topic here! Or this one RE: <POLL>Kaioken 5% Attackspeed first use
Or maybe we should talk about this...okay sry, dont find it directly. But the topic about more budokais in the week...
What is the next vote? Delete all other U-stones, cause we only need 70er versions? So that even lvl1 chars could farm stones?!
I'm the only one who see how damn ez casual this game become?!
This is Dragonball, a game with honor and strength! Normally... 