I am very interested to know why there are still resources that do not allow to use space and other characters, other than Latin characters and numbers, in nicknames / logins. If the fact is that it is necessary to create domains like "username.domain.zone", then I still can not understand it. Because I do not understand why I need this domain. And I would gladly trade my domain for the opportunity to be called not “NickMitin”, but “Nick Mitin”.

The motivation of resources that do not have such domains is not at all clear. Do you solve technical problems at the expense of users (such as captcha, as a means of combating spam), or just go for it?

Anyway
')

What for?