I believe the op's comment was along the lines of "what difference does it make - if you can't tell the difference how can you say it makes a difference?"
To be followed up with the questions of "how will you be able to tell?" and "what are you going to do about it?"
Ok, so would you be ok with someone impersonating your girlfriends emails to you?
I.e. you're getting emails from someone impersonating your girlfriend but they're very good at impersonating her so you can't tell the difference.
Are you comfortable with that, even if you can't tell the difference? Or someone saying they are your mum, dad, or best friend?
If you buy a piece of art and it says it was by "artists name", and then it turns out it wasn't by "artists name", does it bother you? Even if you believed it was by "artists name"?
I think you understand my point. Even if ElevenLabs made a clone of my mum's voice that was impossible to tell the difference, IT would matter to me. I don't care if ElevenLabs tells me "I love you", I care if my mom tells me "I love you". And lying about it or deceiving people doesn't make it any better.
To be followed up with the questions of "how will you be able to tell?" and "what are you going to do about it?"