Why crystal growth tends to be selective for a single species?

Crystals are composed of the same stuff assembled in a periodic fashion.

I understand that there are possible and less possible bonds. Like complementary electric charge, ie. things must stick together or at least not repulse each other.

However I find it difficult to understand why this development process (crystal growth) is that selective and does not result in the assembly of more random bricks together.

I did not find Wikipedia crystal growth article to be helpful.

It seems to me there is a sort of recognition process at hand, and the same element is the optimal choice. My guess is it could be the winner over other bricks by creating the most adherence, while other species would adhere but less stably or not even adhere at all.

I also suppose there are impurities in crystals. I also know some artificial crystals can be fed with a very precise "soup", preventing impurities to insert in the crystal. But this question is not about small defects.

One can find ice or NaCl salt naturally occurring and they are indeed common crystals, so this mechanism does not seem to be highly dependent on the crystal growing in a very unique environment.

Lastly, I acknowledge there is a logical flaw in my question. If it was not the same stuff spatially repeating, it would not be called a crystal in the first place. This is post hoc naming. But hopefully there is more to it, including why crystals exist at all.