Steph: There are a few errors in that text and specifically Tomiki was writing about Judo. He spent quite a bit of thought on how to better train the Aiki techniques without injury and I believe did a pretty good job. Randori, as with Judo, does not use all techniques, but those missing techniques are practiced as intensively as those that are allowed. In fact that is the main difference with Judo training in that Shodokan Aikido is very heavy kata orientated with the addition of randori whereas Judo is heavily randori orientated with the eventual addition of kata. In my opinion Shodokan Aikido training is closer to what Kano had in mind for Judo.
Randori allows us to get as close to spontaneously expressing techniques in a chaotic situation and in combination with kata does not require us to compromise the inclusion of lethal techniques.
If you like diagrams I suggest this
one and this
one. Both are from Tomiki's own work at the culmination of his life's endeavor. In fact I would read the entire site rather than quote someone who was less informed than he thought.