Yeah, although they're called nicknames and can easily be caughy
The main username is what it matters.
Impersonators use some characters that aren't quite noticeable to the people so they could easily impersonate someone and scam people.
I'd never prefer discord for deals although if using it comes as a compulsory to get in contact with client or a seller , I'd recommend you to verify each other on site and then only proceed.
We should be thoroughly scrutinized in every way of doing things, so there is less risk of getting scammed. You are right in saying that scammers are disguised to deceive the common people but more and more new ones are wearing them.
Scammers are very knowledgeable in doing this act, they manage to really let you believe that you are talking to the person that they've impersonating but by doing proper checked and having such awareness to this kind of scamming you'll be able to perform security measures before sending anything to each users that you wanted to deal with. Always be very careful do the routine checks before communicating to anyone especially if you are dealing with money or any important information.