Do You Always Use a Comma before "Because"?

I learned in school that when a subordinate clause comes before the main clause, there must be a comma between the subordinate and main clauses. However, when the main clause comes first, a comma isn't necessary.  I think it's a basic rule.  Commas may be used when the subordinate clause is very long but would not always be used. I see some people always use a comma before "because" but native English never remove the comma. It might be because they think the subordinate clause is very long.  I was surprised that a native English speaker added a comma before "because" even though there were only four words after "because."  Do you always use a comma before "because"?