ballcock

Hello I have 3/8" Female compression & 7/8" ballcock (http://www.homedepot.com/p/3-8-in-Compression-x-7-8-in-Ballcock-Nut-x-12-in-Braided-Polymer-Toilet-Connector-B1-12DL-F/100094502) for my toilet that delivers and stores water for flushing. I have a T-tube (for my Bidet) that I am trying to...

It seems that everyone replaces their ballcock valves with float cup valves, but why? Are float cup valves more reliable? Or are they quieter? Or are they just more convenient because of their form factor? I would think ballcock valves are more reliable because they are simpler and they have all...