Why would the community not provide advice when I ask a question that is limited by an older Perl?

I didn't use the word "advice", but I'll address this anyhow.

From a security perspective, if you ask "How can I harden my 5.8 application against user-input hash DDoS attacks?", the answer is going to be "Upgrade". You're unlikely to get someone to backport a hash seed randomization patch for free.

From a personal perspective, if you ask "How can I perform task $X, but only on 5.12 or earlier", that means I'd have to install an earlier version of Perl and think really hard about how to write something without regex improvements, signatures, postfix dereferencing, improved capture groups, lexical subs, or any of a dozen other little improvements I've grown accustomed to, not to mention code that only runs on newer releases (anything that relies on pluggable keywords, Mojolicious, etc etc.)

I don't see a lot of personal value to me in keeping around 30-odd versions of Perl to backport a solution to, so I'll just ignore it and move on.

That doesn't mean you should or shouldn't use a specific version; just that you should expect you've limited your peer pool when asking these kinds of questions.