You have both totally missed the point and indirectly hit the nail on the head. Aikido IS a capstone martial art, just as I have been saying this whole thread, just as Remy or Dan the Wolfman say in their interviews with Rokas. Even studying one Aikido technique per week, you would likely get through most schools ENTIRE syllabus in one year. Aikido primarily trains movement and specific principles for controlling a confrontation. The original Aikido students all had their blackbelts in Judo when they stepped into their first Aikido class. If you trained Aikido for 15 years as Rokas did, with no other foundation and especially in its weakened, watered down state and with no physical conditioning you would likely end up where he did. No one is putting Aikido on a pedestal and touting it as the most effective martial art and it does not have to be. Aikido fills a niche, it focuses on the beginning, pre fight phase of a confrontation and it gives tools for an already experienced and well rounded fighter to control the confrontation, hopefully in a way where both parties suffer little to no injuries.
The skills learned in Aikido are primarily its principles, its movement and its ways of handling conflict, these principles and methods can be used alongside other martial arts and they should be. All that said, most people are going to end up in situations that can be well served by some of these techniques. If trained correctly, Aikido does what it is supposed to quite well and hence why I have said that I have gotten more mileage out of my Aikido than anything else. Contrary to this discussion, real fights don't usually take place between skilled individuals, they don't last long and most people aren't that committed to finishing them once they start, they tend to look for a way out. Believe it or not, getting tossed onto their butt a few times generally discourages people into moving on with their night. The mental math for how much more pride they want to lose and how not fun hitting the ground is ends most violent confrontations because people can tell when they are outmatched. Simply manhandling someone with a hip throw is going to full stop 90% of bar fights, the guy who gets put on the ground is going to hit the deck, think "oh crap, no thanks" and stand up apologizing or put his hands up in submission. These street ninja fights you kids keep talking about don't happen.
From an ordinary persons perspective it is very useful to be able to defend yourself from a majority of situations without having to engage the fight to the point where you have to beat the brakes off of someone or risk seriously injuring them. If you are someone like a police officer or security guard or bouncer, it is much better to have options that don't require you to exhert overwhelming force, being able to use the appropriate force for the situation is often both prudent and beneficial for everyone. To make Aikido operative you are going to have to find a good teacher/school and put the time in to learn how to apply the techniques, like anything. Just because you aren't going to win the UFC with your Aikido doesn't mean the system has no value.