My subjective impression regarding third-party libraries specifically is that if anything, the situation has improved a lot in the past 5 years, mainly due to Q

My subjective impression regarding third-party libraries specifically is that if anything, the situation has improved a lot in the past 5 years, mainly due to Quicklisp becoming the de-facto standard. Now there's a curated collection of libraries that are tested to work across multiple CL implementations, pull dependencies properly, etc., instead of the previous mess of manually downloading .tar.gz from random places on the internet.