Why YSK: Because some people may want to use old reddit’s interface and might be used to it’s look. To choose the instance, put a /[instance name] after that url, or use the option given by the site itself
edit: apparently the original site where this came from is https://mlmym.org/ and this is the github repository https://github.com/rystaf/mlmym
Whilst it’s not as good a conversion as the one you posted, there’s a violentmonkey script that does a pretty good job too
https://greasyfork.org/en/scripts/469093-compact-lemmy-to-old-reddit-re-format-lemmy-v0-18