It's bad because every implementation fills the gaps in their own incompatible way. And then instead of converging on the "best" solution, the community argues

It's bad because every implementation fills the gaps in their own incompatible way. And then instead of converging on the "best" solution, the community argues endlessly about each unique solution is the best. And it's also bad because CL is ancient and it's filled with things that simply don't make sense any more, or have been replaced by "better" solutions in every other language. Look at filename and filepath handling to see what I mean. 2 or 3 of the fields haven't been used in real systems in 20 or 30 years, yet they're kept around because they're in the unchanging CL standard.