Chat archives are stored encrypted, not in plain text. Please cite your sources if you claim otherwise.
I think that's what the parent wanted to say.
I think saying "chats are stored in plain text" is a reasonable way to convey that message and I think "plain wrong" is an overstatement.
If I keep your messages encrypted in my database and your keys on another unonnected database in another building, would it then be fair to say that I store your messages in plaintext?
No. They are encrypted. It is a matter of fact.
The word you are looking for is "not E2E encrypted" which can be a problem, but a different and smaller problem.
> and I think "plain wrong" is an overstatement.
No. It is a statement of a fact.
If you can still access them, I don't think it is fair (or maybe rather: it is misleading) to say that you store them encrypted.
If you trust me but are worried that someone else might break into the server it makes a huge difference.