The /th/ sound in English and Spanish.

A self-appointed phonetician on Instagram, a few weeks ago,  endeavored to teach Spanish speakers the sound of /th/ as in think, thigh, or thwart. He pointed out that this sound does not exist in Spanish. The phonetician, obviously, does not differentiate casar and cazar, serrar and cerrar, coser and cocer. I do, along with many others. My point is that when comparing languages, we must be true to the two of them. The sound of /th/ in think does exist in Spanish in cazar. True enough that the point of articulation is a bit different: the English sound is interdental and the Spanish sound is dental. And here, once again, I must paraphrase Ortega y Gasset: The horizon of our language is not the horizon of language. And once again I must warn you: beware of unqualified native speakers pontificating on the language they speak.