This is a fair and it's one of the reason why Larry Wall created the alias Raku.
But let's entertain for a moment that there wasn't even an alias for the language. I'm sure we both agree that for a person who comes across the names Perl 5 and Perl 6, the latter seems to indicate that it's the next version of the former. In fact, this is totally excusable. After all, why should the person assume they're different languages and disregard what seems to be a logical conclusion? 6 is immediately after 5 and it suggests some sort of progression. Thus, it was on the community to make it clear and unambiguous to newcomers but I'd daresay it failed at that. Raku is an attempt at correcting that blunder but who can say it will succeed in that area?
Now...
Would it be logical for the same person to rehash the same "assumption" after they already learned about it regardless of the context of the conversation? If you've (you in general) learned that Perl 5 and Perl 6 are different languages, what's the merit behind pointing out the obvious? Again, I'm referring to people who, for one reason or another, already know they're both different languages yet still are set to bring out, whenever the opportunity arises, the same and old "naming" debacle as a reason for people to avoid/bash either Perl 5 and/or Perl 6
When I first heard about C++, I myself was confused on whether it was the next and better version of C. However, it just took me an internet search to realize that C++ and C are two distinct languages. Afterwards, I haven't confused the two anymore. One might certainly argue that version numbers are different to use of operators (specifically, ++) but who decides that? For me, the ++ in front of a language's name implies the same type of progression 6 does over 5.