MaplestoryM Mesos is trivial to have a new ip address, requires only moments, but getting a new phone number is a lot more work, and capital intensive. This puts a massive barrier which only gets more effective over time (as more and more phone numbers are obstructed ) against bot accounts. But it does not hamper legitimate players in all (because, honestly, if you've got a computer which can run MS you've got access to a phone of some kind).
I know there are a number of disadvantages, but I do not think they're big enough to justify not implementing this method. The biggest drawback I can see is a bot/meso farmer uses your contact number and has it banned before you attempt to produce your account. If that's the case, there could be a fairly intensive way to clear a telephone number (it might need to be more intensive to be an effective ban).
Either that or you're out of chance, but the odds of that occurring anyway are slim to none to start with. Also, nexonNA could mechanically prohibit phone numbers from all countries outside of the serviced countries, thus making it even harder for chinese meso farmers to operate (they'd need a large supply of American/canadian phone numbers and corresponding telephones on hand to create more bots).
Ok, I know I have written about Hayato a few times already in the past, however I really, really believe that he's rather underpowered. He is, basically, a fast-paced mobbing warrior. But, that seems to be the only real thing . His 1v1 ability, Shinsoku, seems rather underwhelming, even with Hypers believed and even a decent piece of funding. Specifically, he's got no bind, silence/seal, or so on to counter things like Damage Reflect and Cancel Physical Damage. This endangers him at worst, frees him at least for many major bosses (Empress, Hard Magnus, to mention 2).