As Edwin Ashworth said in the comments, this is, in fact, a case of generic usage. The user here refers to the 'prototype' of a user. Here is how John Lawler explained it on Ask A Linguist:
Definite Generic: the + Singular Noun
The tiger is in danger of becoming extinct.
Plural Generic: 0 + Plural Noun [0 = Zero, the number]
Tigers are in danger of becoming extinct.
Indefinite Generic: a + Singular Noun
*A tiger is in danger of becoming extinct. [normally ungrammatical]
These are constructions, which means that the phrase itself, and
its usage, have special grammar and special meanings. It's not that
the articles the or a have special meaning, really—they hardly
have any meaning; rather, their use in these generic constructions
marks them as special.
As to use and meaning, while there are many, many special cases and
idioms, one can roughly equate the three generic noun phrase
constructions with three different functions. Each refers to some
species (of plant, animal, thing, person, cathedral, or whatever; not
just biological species), but there are several ways of doing this:
The Definite Generic refers to the Prototype of a species,
roughly the image we associate with tiger. The tiger, as a
prototype, has all the properties of anything we would call a tiger,
except that it doesn't exist in an individual physical sense, like all
real tigers do. This is a very abstract concept, and its use signals
that the speaker is theorizing.
The tiger is big means the speaker believes that "bigness", in some comparative context, is a characteristic property of tigers, that we
should expect this to be true of any tiger.
The Plural Generic refers to the Norm of a species over its
individuals, as perceived, of course, by the speaker, who is unlikely
to have conducted tiger surveys, so the "statistics" here are very
vague and impressional.
Tigers are big means the speaker believes that, on the average, any tiger is likely to be "big". This doesn't mean all tigers are big,
though that's close. This is potentially a less abstract concept,
since its use implies a generalization based on experience of several
The Indefinite Generic refers to the Definition of a
species, that is, those properties that are absolutely necessary for
anything to be a member. It doesn't work as the subject of any
predicate that isn't definitional. But with a definitional property,
it's certainly true for any member.
And that's one of the reasons why [the following] sentence is
ungrammatical. If one says
*A tiger is in danger of becoming extinct.
one is saying that being in danger of becoming extinct is one of the
defining characteristics of tigerhood, which isn't true, after all.
Tigers would still be tigers if they weren't endangered.