The mobile site allows viewing of talk pages via an overlay designed to make large talk pages more readable.
When visiting the talk overlay and clicking a talk topic the talk topic is shown in an overlay.
We purposely use #!/talk/1 to mean open the first section in the mobile talk overlay while still allowing #Talk_Topic to point to the actual section on the talk page.
Apparently, people copy and paste the URL from mobile and paste it into wikitext... but this doesn't work on desktop.