Why preterite here?

[BlueSkies]

Una gran mayoría quería cursos de informática para no quedarse al margen de las nuevas tecnologías. Estos no se habían organizado porque se consideró que ya había numerosos centros de mayores que ofrecían cursos de informática en diferentes niveles adaptados a nosotros. No hubo suficientes cursos a niveles avanzados para satisfacer la demanda. Se ofrecieron demasiados destinos de viaje y hubo muchos que se tuvieron que suspender por falta de participantes.

My grammar book (aimed at intermediate level) offers the following rules

Preterite
To locate events in the past (Picasso nació en 1881)
To refer to single complete actions in the past (Ayer me levanté tardísimo y perdí el autobús)
To refer to events that lasted for a specific period of time (Trabajé seis meses en Caracas)

Imperfect
To describe people, places, and objects in the past (De niña, Marta era alta)
To refer to habitual actions in the past (Todos los días jugábamos después de la escuela)
To refer to an ongoing action or state in the past, whose beginning or end is not specified (En aquella época vivíamos en un piso en el centro)
To set the scene in a narrative in the past (Era sábado y hacía buen tiempo)


I have a problem understanding the end of the passage. No hubo suficientes cursos a niveles avanzados para satisfacer la demanda: no specific time is mentioned here, so why isn't this considered 'an ongoing state in the past, whose beginning or end is not specified'? Likewise with y hubo muchos...

Finally, que se tuvieron que suspender: isn't this an habitual action in the (unspecified) past?


Help much appreciated, thank you.

[Niiko]

Well, the differences between them and the usage is one complex subject. In the cases you're asking, it has to do a lot with the preference of the speaker to punctualize the situation (or maybe because it only happened once), he wants to speak about a particular time when there was a lack of courses and a particular time when too many travel destinies were offered, without explicitely stating how long these situations lasted, but the presence of preterite still tells us that it had a punctual beginning and a punctual ending, and that's what the speaker wants to convey.

Also, if this helps you, preterite is used when narrating facts in the past, imperfect is used when describing in the past (among a ton of situations when one or another is used).

[BlueSkies]

So if it is largely a case of preference here, does that mean the sentences would be equally correct if the mentioned examples were changed to the imperfect?

[Niiko]

Wouldn't be equally correct because, while very very subtle, there are differences but for the most part, everyone is going to easily understand what you're saying regardless which one you use.

As I said, have this in mind, preterite narrates facts from the past and imperfect describes a situation or something in the past.

For example, if I said to you, "Yesterday, I ate an apple" or "Yesterday I was eating an apple", you know there are diffences between the two sentences but you would still understand even if I use the incorrect one. Another example could be "Last year, I walked every day to school" and "Last year, I would walk every day to school", once again, subtle differences, but still it's pretty clear what I'm trying to say regardless, these are the kind of differences between preterite and imperfect in Spanish, so don't worry too much, even native speakers would've trouble understanding the differences, it's one of those subjects you learn better from experience than from a textbook.