Is there any reason why non-global/first-occurrence substitution is the default in many text editing programs (vim, sed, perl, etc.)? I am talking about the /g flag of search and replace commands like:

:s/pan/focaccia/g             # in vim
sed 's/sfortuna/fortuna/g'    # with sed

that will substitute every occurrence of the search pattern with the replacement string.

After (not too) many years of vim and sed usage I still did not find any use case for non-global substitutions. Is there some valid historical reason? Or it is because it is?

Thanks.