The car analogy is one I commonly see, but given the relative cost of service to value of the item, it is no where near appropriate. It makes sense to regularly do a $200 preventative maintenance to protect your $40k car. But spending $300 to every few years to service a $600 watch, not so much.
Car to watch analogies are generally not very good, and I agree that the service one is terrible from a few directions. For one, those who say to service a car is only a small percentage of the car's value, and compare that to watch service and the percentage of value of the watch, aren't comparing apples to apples.
If they were, your average car service would involve tearing the engine completely apart, replacing or repairing all the worn parts inside, bringing the engine back to up to the original HP and torque specifications (no matter how old it is), and then taking the body apart for changing of all seals as a start, and possibly a complete refinish of all panels. That's what is involved in a watch service, so to compare that to anything but a frame off restoration of a vintage car, is a very poor comparison indeed.
Also, the idea that failure to service will result in "major repairs" is just not true, at least for the vast majority of watches. For most vintage
Omegas, a routine service will fix most problems, plus maybe a few inexpensive and at least for now, readily available parts.
Of course people can believe whatever they wish, but with vintage watches in particular, even the parts that are still available from Omega are getting very expensive. I'm all for letting modern watches run until they stop, use the service center, and you won't pay a penalty in costs, but the same simply isn't true for vintage watches.
It used to be rare that the value of parts in a service job equaled or was more than what I charge for labour, but now this happens often. Here's an example - this is a winding gear for the Cal. 1010 series of movements...
This part is over $300 itself...and like any reversing wheel is one of the hardest working parts inside the automatic winding system, so they frequently need replacing if worn. I don't think vintage collectors have any idea of what it's going to be like in the not too distant future regarding parts prices - these increases are happening at an alarming rate. Replacement crystals just recently went up to a crazy price - what you used to be an easy decision to replace a crystal is now something that can really impact the bottom line. A third wheel from a Cal. 321 that I used to get for $38 as recently as February of this year, is now $180.
More than ever failing to service in a way that preserves the parts inside these vintage watches is going to cost people a lot of money in parts. If you choose to not service your own vintage watches regularly that's fine, but say that the parts are inexpensive, is not really the case anymore.
Cheers, Al