I think if you can do something reasonably well, you should do it. It may depend on region (and that my day job isn't lucrative), but where I am hiring people is incredibly expensive. I'll hire for things I can't do competently (most plumbing) but it almost always makes financial self to do it myself. In a recent Saturday, I estimated the cost to hire out everything I did would have been $750-$1,000. I don't make that much in a day, maybe you do. Plus, I still have to supervise, let the person into the property, find the person to do the work, pay them, enter the payment into Quickbooks, etc. I'm not really saving time.
Also the first post seems to compare the pretax value of their time to the post tax cost of hiring people. If it is maintenance that is expensed on the tax return (and you don't have losses over 25k that you are rolling forward, then you should compare apples to apples post tax. For people with a fixed salary that have some extra time on the weekend that enjoy the maintenance and are decent at it, and don't have big family responsibilities, I don't think there is much opportunity cost. If it something you have to capitalize, then the advantage shifts to doing it yourself. For example, say I'm building an addition, and I have to capitalize it over 27.5 years. If I work less hours at work during that time, I'm making less by the after tax net amount of my wages. But I'm saving an amount that is almost the before tax amount of what I'd pay someone, because due to the fact that I'd have to depreciate the expense over a few decades, much of the tax value of the deduction from hiring someone to do the addition will be eroded by inflation. Finally, I have to pay social security tax and medicare taxes on money I earn, which will either not pay me back well or will do so at a time several decades from now when I have more money than I need due to smart investing!