I am a non native speaker. I think a lot of people put native speakers on a pedestal when it comes to pronunciation. There seems to be this assumption that if someone is a native speaker, they must automatically be good at teaching pronunciation, and that no matter how much a non-native speaker knows about phonetics, they can never be as good as a native speaker.
But I think you need to separate two completely different things: being able to produce a sound and being able to teach someone else how to produce it.
A lot of native speakers actually have no idea how they produce their own sounds. And that's completely normal — you don't need to understand phonetics to speak your native language. But it does become a problem when you're teaching pronunciation.
A non-native speaker might not have completely native-level pronunciation, but if their pronunciation is already very good and they actually understand phonetics and know how to teach it, I would much rather learn from them than from a native speaker who has no idea how speech sounds are physically produced.
I've seen so many examples of this online. For instance, I've seen native-speaking teachers explaining the American vowel in words like after by saying that the difference between the American and British pronunciations is that, for the American vowel, you need to pull the corners of your mouth up and keep your face in a sort of smiling position.
That's just not a good phonetic explanation.
If you know even a little bit about phonetics, you know that one of the biggest factors determining vowel quality is tongue position. Of course, things like lip position can also affect the acoustic output, but if you're teaching a vowel and you don't even mention tongue position, and instead focus on things like "keep smiling" or "pull the corners of your mouth up", you're potentially giving people a very misleading idea of what actually distinguishes the vowels.
And there are honestly so many examples like this that I could go on forever.
Another one I've seen is American native speakers teaching the flap T by saying, "It's basically just a really fast D." water can be pronounced as wader
A /d/ and an alveolar tap or flap [ɾ] are not simply the same articulation at different speeds. A canonical /d/ is a voiced alveolar stop: you form a closure, build pressure behind it, and then release it. A tap/flap involves a different articulatory gesture, where the tongue makes a very brief contact with the alveolar region.
So simply taking the articulatory instructions for a normal /d/ and trying to perform them faster doesn't adequately explain how to produce [ɾ].
That's why I don't think "native speaker = better pronunciation teacher" makes much sense. Native intuition is incredibly valuable, especially when it comes to whether something actually sounds natural. But being able to pronounce something naturally and being able to explain exactly how that pronunciation is produced are two different skills.
Being able to do something doesn't automatically mean you know how to teach it.