> Nobody forces you to use iMessage/Telegram/WhatsApp/...
The EU strongly disagrees with this statement in case of the the latter two, which is why they are being targetted by the DMA and must provide interopability so that you cannot continue to be forced to use them.
If iMessage had users in the EU, the same would have applied there.
Being forced to use something does not mean you are being held at gunpoint or that no other options exist. For messaging apps, being in a location where your entire social network uses one app is indeed a case where the average person ends up forced to use that app as picking another option means not talking to your social network (unwanted) or having to convert everyone else (unreasonable). This harms both competition and users.
The EU strongly disagreed about many things that it later admitted were wrong (or just quietly changed its stance on), for example nuclear energy policy or biofuel additives. It also kind of does its own thing without really consulting the general population. Practically nobody even knows what's happening there in my country.
"They have previously been wrong, therefore they cannot be right" and "I do not know what they are doing, therefore they cannot be doing the right thing"?
I think that clearly marks the end of any useful discussion.
iMessage is a service that allows your phone to connect and send messages to other iMessage users.
Use email if that's what you need. Nobody forces you to use iMessage/Telegram/WhatsApp/...