This is paltry nonsense. Gmail and similar host users are used to treating the dots as decorative, and will register with john.smith@ then try to use "Forgot username?" with johnsmith@ instead. They'll end up with three GitHub accounts registered to the same mailbox and be confused as heck about how they're still getting email notifications for an account that they can't recover a password for.
You can't break user expectations and mental models by pointing to the spec as justification. The spec exists to serve users, not the other way around.
You can't break user expectations and mental models by pointing to the spec as justification. The spec exists to serve users, not the other way around.