I get that, but Reddit will be (and has already been) monetizing the content you created. They will also be selling the content to LLMs (large language models) to train AI models. So while I agree you are doing a disservice to people looking for useful content, you are also allowing Reddit / spez etc to monetize your content while giving a big finger to mods, volunteers, communities and 3rd party app developers.
shreddit - you need to register for an API key (client ID actually) and download the app, but it is very simple and available for MacOS, Linux and Windows. It’s using the API to delete your posts and comments, you can do a dry run to see what will get deleted.
The cherry on top of the cake is that it using the much discussed API, so use it while it is still free and give spez the finger by deleting your content using his precious API.