Using a transistor as diode
One advantage can be found: In linear scale there's very sharp knee in the forward current vs. voltage curve. In logarithmic scale it's quite a straight line. I had once to build a safety circuit to an existing custom digital display resistance meter. The safety circuit had to guarantee the meter will never output more than 1,5 volt to the device under test.
The safety circuit was needed for 2 reasons:

people in a factory wanted to see something so simple they could understand and verify. Digital measurement devices and integrated circuits weren't such things. Those people made detonators.
there was internal safety code which said that the open circuit voltage must be 1,5 volts or less, no matter there's resistors and a fuse which would limit the current in case of faults. That wasn't a problem with devices which used only a single 1,5V battery. Electronic devices needed more.

The resistance meter was a DVM with a current source. It had a differential preamp to scale the result to DVM's range from the usual measurement voltage level.
The safety circuit was not allowed to disturb the resistance measurement. Usual diodes and zener diodes conducted too much and no complex circuits were considered reliable. A transistor base and collector together  (actually 2 transistors) were considered to be a good enough last resort limiter:

A and B were soldered directly to the test connectors.