Ever since the fuel pump was moved to the fuel tank, fuel pressure replaced the float height as a measure of fuel system health and performance. Checking the height of the float might have required some disassembly or special tools to bend the arms of the float.
When the shift was made to port or throttle body fuel injection, all a technician needed to diagnose a fuel problem was a set of “noid lights,” a fuel pressure gauge and maybe a multi-meter. Measuring the fuel pressure typically required checking the pressure at idle and under load. Most of the these tools can’t be used on the high pressure side of a direct-injection system because of higher pressures and changes in the injector location and technology.