The use of because as a subordinate conjunction is quite appropriate. It is correct grammatically and is in common usage as well as collegiate usage.

Illustrating for you:

Because of too much rain, many crops have been ruined. The verb phrase have been ruined is modified by the because clause. The clause is a subordinate clause which requires an independent clause to which it may bring modification. The independent clause is many crops have been ruined. That independent clause stands on its own. It may be written as a complete sentence.

The subordinate conjunction “because” introduces the entire subordinate clause in the illustration. It is grammatically correct.

Should you wish to argue otherwise, you must demonstrate that the word because is something other than a subordinate conjunction. I doubt that you can do that. The verb phrase “have been ruined” is modified by the word because including the complete subordinate clause which includes the prepositional phrase of too much rain. If the format of this forum permitted, I could diagram the sentence for you in standard English diagram used to show relationship of all words in a properly written sentence.

What grammatical analysis can you offer to support your assertion, “It has always been wrong”?