It's possible to do that without spying on your users, e.g. by storing them encrypted.
Do you have a source for the claim that message do not have encryption at rest?
Discord explicitly confirms in its privacy policy[1] that it collects the following information:
IP Address
Device UUID
User's e-mail address
All text messages
All images
All VOIP data (voice chat)
Open rates for e-mail sent by Discord
[1] https://discord.com/privacyThe "convenient history of all the messages" does not require a service having access to your messages.
Besides, "tu quoque" is a really weak way to carry an argument.
Anyway, ample chances were given to understand your point, but you seem to value having the last word more than having a conversation. So there, reply below and "win" whatever imaginary prize you wish:
That said, E2E-encryption doesn't come without drawbacks, for example you would lose all your messages if you lost access to your device and any backup mechanism.