In the sense of modern DAWs/VSTs, sure, but in the sense of the synthesizer as a standalone instrument, its absolutely not designed to reproduce the sound of other instruments. Its an electronic device that outputs specified parameters. Whether that happens to coincide with parameters set by other artists/instrumentalists to 'reproduce' other tonal profiles, that's a byproduct, not a feature.

The spirit of the comment you're replying to is admonishing AI's use of pre-existing melodies, harmonies, chord progressions, and musical themes from songs that were fed into it.

Be it Beethoven (which is in the public domain so hey, free game) or Sabrina Carpenter (very much not in the public domain, but arguably not musically complex), its taking pre-existing tunes and regurgitating it into something else.

This isn't really true in general, especially not nowadays. Plenty of synthesizers are not designed to sound like another instrument.

Try this: go out and take some sounds off the internet, don't pay the people who recorded those sounds and make a synthesizer out of them, and sell it. Let the people whose recordings you stole know what you did, and see how that works out for you. The lawsuit will be straightforward.

Now, go out and take those same sounds off the internet, don't pay the people who recorded those sounds, and use them to train an AI, and sell it. You're still a thief, but now it's much harder to prove you're a thief, and lots of AI investors will invest money making sure that courts decide you're not a thief.