Last time I checked on it, QuickLisp doesn't support fetching packages over anything except for plain http, with no encryption and no verification mechanism in place to detect files that may have been tampered with during transmission.
I think not supporting encryption or authentication for something as important as fetching source code makes QL a non-starter for me and hopefully for anyone else who cares about security.
Another issue I have ran into, is that SBCL is hosted on sourceforge, which has in the past injected malware into projects downloadable archives! I consider this to also be a security issue, and sourceforge in general is not pleasant to work with. I don't think there are any valid reasons to continue to use sourceforge today, so why such an important project continues to use it confuses me a lot.
I don't see these issues mentioned by anyone else which is bizarre to me.
I really like lisps and common lisp specifically but things like this has driven me away from using it and it doesn't appear that anyone cares about fixing these things.