Say you read a bunch of code, say over years of developer career. What you write is influenced by all that. Will include similar patterns, similar code and identical snippets, knowingly or not. How large does snippet have to be before it's copyright? "x"? "x==1"? "if x==1\n print('x is one')"? [obviously, replace with actual common code like if not found return 404].
Do you want to be vulnerable to copyright litigation for code you write? Can you afford to respond to every lawsuit filed by disgruntled wingbat, large corp wanting to shut down open source / competing project?