So what’s that about WordPress not allowing certain web link types

Wordpress Logo(aka URI or protocol handlers)

First released with WordPress version 3.3, December 2011, the wp_allowed protocols() function/feature.

You can only link with the following:

  • fax
  • feed
  • ftp / ftps
  • gopher
  • http / https
  • irc
  • irc6
  • ircs
  • mailto
  • mms
  • news
  • nntp
  • rtsp
  • sms
  • svn
  • tel
  • telnet
  • urn
  • webcal
  • xmpp

(list as at WordPress 5.6)

Yes, you can program around the limitation by customising your WordPress installation.