I'm pretty sure the PPM references he supplies are talking about the radio side of things, which is not quite the same as the servo side
They're exactly the same - in the Old Days an R/C receiver's decoder was simply a TTL counter, with the serial pulse stream from the RF connected to the counter's input and an RC circuit attached to the reset pin.
The servo PPM control pulses from the transmitter were sent sequentially in a frame with a long inter-frame gap; the gap was long enough for the RC circuit to trigger the counter's reset and so resync the link.
The output pins of the counter were connected directly to the servo control pins.