You urgently need to update your prejudices, then you will spread less misinformation.

But when someone is already called "epicshitposter", you can't expect much competence.

"no multiple accounts/profiles"
That's wrong. Anyone can install 2 versions from the Appstore Threema and Threema Work. And then have 2 Threema IDs. For example, to separate private and business communication.
Android User can even install ThreemaLibre for a third ID!

"only client is open-source"
That is correct. But the source code for the server is of no use to anyone, because no one can verify whether it's actually running on their production servers. The same applies to other messengers, such as Signal!

"no post-quantum encryption"
It doesn't even exist! Anything that can be encrypted can also be decrypted again. This has less to do with the messenger than with quantum technology.

By the way:

"Researchers use a Commodore C64 to calculate a quantum computer - and annoy IBM with it

Researchers have beaten a quantum computer with an old Commodore 64. The experiment is a friendly dig at IBM, which has claimed that only quantum computers are capable of performing such calculations."

See (unfortunately only in German = please translate for yourself):
https://t3n.de/news/forscher-c64-berechnung-quantencomputer-ibm-1619710/

"only f-droid ver. comes without proprietary libraries"
This is also outdated. The version from the Google Playstore can also be configured to work without Google.

"centralized"
Right, because with Threema this is a security feature. It always depends on how an operator handles it!

There may be spy servers in federated systems that collect your data, see Signal or Matrix. I wrote more about this above.

You can also host Threema on your own server:
https://threema.ch/en/onprem

"maximum number of participants group chat is 256"
That is correct. More users makes no sense. If everyone writes something, no one can keep up anyway!

"not the best at protecting metadata"
What makes you think that? Threema is the only messenger that doesn't store any metadata.

Threema only stores messages until they have been delivered to the recipient.

And most importantly: Threema is the only messenger that does not store any metadata or IP addresses.

If you communicate digitally - and we all do that today - and don't want to leave any traces behind, there's no way around the Threema app. 

"no screensharing"
Threema is programmed for the greatest possible data protection, which of course also means that no one can read your screen (except you). Android users can also activate the screenshot lock.

"destructing messages"
So far, there is no implementation of self-destructing messages that offers real, reliable security and goes beyond gimmickry. 

Even if a message has disappeared from the chat, it remains in the notification log of the cell phone operating system, for example, and can be read by third parties using simple means. 

This lulls you into a false sense of security. As I said, false security is not our thing.

"paid"

There is no such thing as a "free messenger" - there are always some data collectors behind it!

Look where the money comes from = Look who´s behind !!! 

Threema has no dubious financier in the background and is therefore completely independent.

Private users pay a one-time fee to ensure that they are not spied on.

What are the few dollars for Threema compared to being permanently spied on by all the other messengers?

If you want to buy Threema with sats, you can do it from me:
https://primal.net/e/note14r3uwldurcseuuu9wzntgjsacag3wh3yesrezs5y3ukde6zgmk2sw5708f

or note:
note14r3uwldurcseuuu9wzntgjsacag3wh3yesrezs5y3ukde6zgmk2sw5708f