Just connecting the Pi to an HDMI device will not provide any sort of touchscreen facility - HDMI is output only, and the touchscreen data need to get back to the Pi somehow. When connecting a HDMI monitor with touchscreen, usually there is a USB or similar connection as well.
Principal Software Engineer at Raspberry Pi (Trading) Ltd.
Contrary to popular belief, humorous signatures are allowed.
I've been saying "Mucho" to my Spanish friend a lot more lately. It means a lot to him.