I just found out I cannot delete my post

[Jokers]

Looks like our experience are difference. Many forums i've used which use "modern" software (e.g. Discourse) or has more modern UI let user delete or edit post with little limitation. Although i guess it's partially because they decide to comply with GDPR or other privacy laws.

That's right, most of forums I communicated on were of previous generations like Invision Power Board, vBulletin, phpbb, etc. But it shows at least that the way of dealing with those options can be different. As a mod I can see many disadvantages in deleting or editing of posts older than several days, because it can lead to different manipulations, but if you'll convince admin, I'll be okay with that as well.

[KingsDen]

I like the fact that posts can't be deleted though. Because many users post by plagiarism but later try hard to delete their post but still can't. So I think it's a very good thing not to have this delete icon so that no user can steal other's work and delete it later.

If someone plagerise and later became remorseful and decides to delete the post, I think it shouldn't be an issue. In a forum like this that we are clamouring for growth, we should try to be lenient rather than trying to victimize. I am not justifying plagerism because I am a preacher against it and I have created so many topics against it in BTT.
I personally do not have any issues with deletions since the modify option will always work. I'll just edit the whole text to a [.]