I’m new with UR so sorry if this question sound strange.
Why should I write an Urcap application in order to start a daemon (and start a communication with it using free tcp socket) rather than installing my application as a linux daemon ? It seems to be more simple.
URCap daemons are the only recommended way by UR.
Other options may be possible, and if it is your robot, you can use it in your preferable way.
But the officially supported way is through URCaps.
If working on a potential UR+ Product, pay attention to that only URCap based daemons are accepted for Certification,.