Every script kiddie after a single class in uni knows how to make one. That's why reddit had so many annoying bots that did fuckall but tried to be funny.
Reminder bot at least had a purpose and had to be manually triggered by someone to act. I'm talking about the annoying ones, like the spelling bot, it just scraped as much as it could, looked for common spelling errors and corrected people. Good thing bots were getting banned left and right. People aren't original. When on /freefolk the Bobby bot got successful via a meme, there were like 10 other copycats the next week, made by people who didn't know that nobody called the character "bobby" unless they wanted to invoke it. So then, a bot would pop up for writing Tyrion, Cersei, Tywin, etc, which were used always, since it was a fandom subreddit.