You're right for the most part.
But........There are many people who don't want, cant afford or are unimpressed with warranties that usually only include parts and come with expensive labor charges after only one year. New equipment has been plagued by faulty high efficient motors, TXV problems among other things, and have not impressed me for one. The vast majority of people that I see choose to spend a relative small amount of money a year for refrigerant rather than thousands for a new system. Or would rather just change the condensing unit if they can, especially if their indoor units are only a few years old. There is a big market for people who don't want to spend thousands. Personally, I make a nice income from it and have many happy customers as a result.