So you're fine with money laundering as well? Because parallel construction is inadmissible evidence laundering.
Is this your best effort attempt at assuming good faith?
> "parallel construction is inadmissible evidence laundering."
Well, it's concealing a source, which is what I said. If you have an informant who's life would be in danger if they were revealed, then anything they tell you would have to be paralleled. There's nothing illegal about their evidence, they would just never testify to it.
Your position seems to be that there are legitimate reasons it was introduced. I don't disagree with that. That doesn't mean that the process doesn't involve lying in court to deprive people of their rights.
You say "conceal a source" but that is precisely depriving the accused of their explicit constitutional right to be "confronted with the witnesses against them".
(I will note that I've definitely been speaking with a US focus - not all of my comments will generalize.)