Cryptopia ask a lot for confirmation for many coins, not only for bitsend.
It's not like it's possible to double spend over 10 confirmations. i dont see why this is necessary.
Actually it has happened with bitcoin gold. Not sure on which exchange.
I don't remember how long ago, but some people actually did a 51% attack, sent a huge amount of btg on an exchange, traded it and then forced an alt chain sequence to get them back. They probably had a very low requirement, maybe 1 or 2 confs
It would not have happened if the exchange had many confirmations requirement.
I agree that 10 is "probably" enough for the big coins, but now that there is a history of this, better to play it safe