I agree that "no home brewer with a normal budget can really afford a device to measure dissolved oxygen", but I disagree with you final conclusion. You can make beer without adding any oxygen, or even splashing it around. The point is, we are discussing OPTIMAL oxygenation strategies, based on published research and professional brewing practices. I may not be able to reasonably purchase a dissolved oxygen meter and test every batch of wort before pitching yeast, but I can read the research of people who have one and have researched which practices get closest to the recommended values. When I dedicate my time and effort into making beer, I want to make the best beer I reasonably can. That means finding the best practices that are within reason (and budget) to make my beer. As to yeast and oxygenation, I purchased a 5 micron stone and a Pure Oxygen delivery system. This is the best method for delivering the RECOMMENDED level of oxygen to your wort. I know that not everyone has one, and if you dont that's fine. The point is that you should use the information that is available to you to make the best choices for your system, based on what you have. I dont think that anyone here would say that the best practice is to slowly drip cooled wort into their fermentors for 20 minutes. You'd risk infection less and get more dissolved oxygenation by running the wort into your fermentor as quickly as you can and then shaking it for 5 minutes. You will make beer though.
You also mention the possibility of over-oxygenating, but that is very unlikely if you are oxygenating a full batch of wort (vs just a starter), unless you completely ignore recommended practice (1 liter/min x 1 minute through a diffusion stone).
Over-all do what you like, and do what works for you. The OP was referencing using his yeast for multiple generations, and insufficient dissolved oxygen during the reproductive phase of yeast decreases overall yeast health in future generations, meaning it will affect attenuation, flocclation, and fermentation time in future batches. You may not be worried about using your yeast for future generations/batches, but the OP was.