I’m pretty sure Spanish Stack Exchange is for Spanish learners to ask and answer questions about the Spanish language. So why would it prefer questions in Spanish? Why would a forum for Spanish learners want the questions to be in Spanish? That doesn’t make sense to me. Can someone please explain? Also, why does Spanish Stack Exchange require tags to be in Spanish?
Why would a forum for Spanish learners want the questions to be in Spanish?
Well, that's not the site's only purpose:
Spanish Language Stack Exchange is a bilingual question and answer site for linguists, teachers, students and Spanish language enthusiasts in general wanting to discuss the finer points of the language.
Besides that, asking, answering and reading Spanish posts is a great way to do immersion. Yes, you (and I, and other learners) would be able to read posts in English much faster than posts in Spanish, and understand them better. But for our overall progress in learning Spanish, it's better to use Spanish. Tag names help a little too - it's one of the few things the community can contribute to what a user experiences as 'the system' (unlike e.g. button and label texts, which are always in English).
That said, a question being in English or in Spanish should never matter to determine whether it's on-topic or not, nor should it influence voting.
As a Spanish learner I really value questions and answers by Spanish speakers especially from a Spanish speaking country other than Spain like this one
I can learn all the standard vocabulary but it becoomes harder to read the papers when you don't know who the people are that are involved especially the politicians. Their names are not in a dictuionary anywhere. Once you know who Señor Sanchez is, reading the Spanish papers becomes so much easier.