No, a PIFA is very depending of its ground plane, but the part of main PCB that have an antenna structure above, is also used for 10 other things in high density electronics. Actually is whole metallic construction in a cell phone also a part of the PIFA structure.
It is not unusual that whole PIFA structure is etched on PCB, but not same PCB as main board.
FIFA can however be etched by using only a single PCB layer.
Can sometimes be seen as BT/WLAN antenna in low cost phones but also as main GSM antenna in M2M solutions were space is almost unlimited without increasing any cost.