Dominic Chapman quotes Shioda and then comments wrote:
"Aikido must not make the same mistake as Judo which, although it has achieved growth as a sport, places too much emphasis solely on competitions. It has abandoned effective techniques that could actually be used in a real fight and has become ineffective today as a martial art."
This is only a short extract (and i highly reccomend reading the rest) but the long and short of it is that even though competition can be hotly contested it can never compare to real combat which budo tries to train you for. Rather than training to be good at competition.
Shioda doesn't seem to disagree with Tomiki here at all. Phrases (albeit in translation) such as too much emphasis
suggest balance rather than total exclusion.
Where that optimal balance lies is a matter of opinion - at Shodokan Honbu well over 90% of the training is drills and kata but the remaining portion devoted to randori is believed to make all the difference. The technical, physical and emotional lessons learnt applied to all ones aikido.
It's a given that if you train for a very narrow goal you could face trouble if the parameters are changed but it is mystifying to me how excluding competitive training can better prepare you for real combat