PHP is broadly used for Web Sites and has a great adoption - Perl Community doesn't need to convince them they are inferior

They already know PHP is inferior, and kinda brag about it:

"This is PHP, surely you didn't expect any sort of internal logical consistency."--Official PHP@ twitter.com/official_php/status/1019024916811866113?s=19

But all that adoption (of Perl's mojo) not so great:

"Around 62 percent of all Internet sites will run an unsupported PHP version in 10 weeks"-- www.reddit.com/r/lolphp/comments/9occ0x/not_sure_if_lol_but_seems_relevant_around_62_of/

The language a professor uses in his class is not an argument against all other languages

Maybe not, but apparently that IS how it's being presented by the professors, and the corporations they work for:

"as a condescending executive told me in college during a business presentation, no one uses PHP, Perl, etc. anymore. It's all enterprise shit with hellaciously expensive servers and support packages."-- developers.slashdot.org/comments.pl?sid=639163&cid=24513115

It is not the role of Perl to market itself as 'better' or defend against people who choose not to use it

Maybe, maybe not, but that IS the role of us Crusading Warrior Monks! ;-)