Personally, and I realise I'm not speaking for every member of this forum, I hate companies pushing Discord on me. I don't want to chat or spam emojis and reaction GIFs, I just want to post questions, and also answer questions other people post. There's nothing that needs my phone spamming notifications every 5 seconds.
</grumpyOldManMode> 😇
EDIT: Also, the vast majority, if not all, of osTicket users will be doing so for work reasons. Not a lot of companies will allow employees to use Discord during work hours.