Actually, ". matches any single character" is simpler.

Clearly so, if taken in isolation. However, I came to Perl like many others through the time honoured journey starting at sed and passing through awk. Therefore to me it is consistent for standard (ie. modifier-less) regexen in Perl to be entirely compatible with sed and awk and if that makes the \n exception for . necessary then it's a holistic simplification for me. The point that it is not so for others is well made, however.

[indisputable] was also intended for comic effect :)

TBF, I was about half way through my previous reply and was about to point out the many discussions in these hallowed halls regarding the opinionated nature of some of TheDamian's considerable output when it occurred to me that you were probably joking. If it took me that long to spot it, a relative newcomer would have no chance and would almost certainly have taken you at your word. I'm glad therefore that the subsequent discussion has cleared that up. Thanks.