Interesting question. I think there is some bias in the question, in the sense that the person who wrote it, like many of us, started in 3 rail O back before there was command control or got into it because at the time CC was too expensive, and I guess the idea is that over time you slowly expand your knowledge and learn as you build and grow so you learn the idiosyncrasies, learn how to give them the proverbial kick in the pants to get them going again, and thus be able to handle anything that comes up.
The thing is, given that command control has been around for over 20 years, there are a lot of people entering or in the hobby that have never been around conventional, weren't attracted to it, and thus are thoroughly in the modern mode with all its quirks. I don't think cleaning the commutator on a pullmor motor or fixing a sticky e-unit really has relevance to the modern trains, and I don't think that someone buying modern equipment is 'buying their way in', they reflect what the market is today. And yes, there are people who are well off enough that rather than build a layout, they can afford Trainworx building them a layout because they have the money and don't have the time or will to build one. There is a disadvantage to that approach, that unless the company that built it is available to trouble shoot or has thoroughly documented what they did (and I know nothing about what such a service does or doesn't do, couldn't afford it even if I wanted to), can be hard if things aren't working right, someone who built it would know more about debugging. It is a trade off, because that person might not have the time to build a layout themselves so by 'buying into it', they have trains they can run and a layout *shrug* .
One analogy to modern trains I can think of would be with cars. Lot of people did get their knuckles dirty in the old days, repairing them, and you also ironically learned to work around the problems those cars had, like trying to cold start an engine with an automatic choke. The difference is that with modern cars, that are quite complex, you don't need to get your hands dirty keeping them going because they are so reliable and they are very difficult to repair to boot. Where the analogy fails is that modern equipment is complex but it is more like older cars then it is like modern ones, it is complex and quirky and it is difficult to troubleshoot and repair in a lot of cases. Like with old cars, owners have figured out ways around the quirks, but that is a sad testament to what these units are IMO.
Like anything in this hobby, the better way is what works for someone. Will someone who 'buys their way' into the hobby be frustrated when the equipment shows its kinks? Yes, but the sad part is they shouldn't have to. Someone should be able to have a layout built for them and buy equipment and have it run if they don't have the time or inclination to build it. If someone bought a high end home theater setup and it behaved like the toy trains seem to be want to do, there would be **** to pay (fill in your favorite 4 or 5 letter anglo saxon word). For someone like this, buying their way in may be the only practical way for them to do it. I honestly find it kind of sad that in the 21st century that we have equipment in this hobby that is as quirky as a Saab 90 or an Italian sports car of the day. Given the quirks of these things, it might be better to start slow and build up your collection (heck, I have no choice but, not gonna be spending 2k on an engine myself, prob be all used equipment when I go into buying mode again) and learn how to deal with it, but in the end that might keep a 'buy into it' person out of the hobby.