[aoriste]

I do not see that a space makes much of a difference.

Plenty of linguists would admit 'login' as a verb. There is very little difficulty in accepting that 'to log in' and 'to login' mean the same thing.

In this case "in" does not function as a preposition, it is part of the verb. The evidence for this is immediately apparent when we consider that "to log" and "to log in" really are two different activities. We do not mean that we record anything when we login to a machine, what we are doing is obtaining access to it by means of an exchange of previously established authenticating information - and while this step may involve making a record of our login, it need not for the basic sense of that action to remain intact.

Also, we have no trouble with a multi-word verbs in English, if you don't believe me, try googling 'phrasal verbs'. This article is either a gag, or really is just an example prescriptavist nonsense which attempts in futility to combat the last 50 years of linguistic consensus.