You are correct.
The history with smart phones since the day of Windows Mobile (not going back any further), is that there was no incentive for the manufacturer to continue updating the software on their phones. For example, the Compaq iPaq and later the HP iPad, didn't get frequent updates, and the builds were always far behind the current versions.
Later I got an HTC Touch Pro II. It only received one update in the 2+ years I owned it, and it was 2 versions behind. The phone was capable of running the latest version of the software, but the manufacturer didn't have an incentive to keep developing for it. And forger about Tech Support. You had to call your cellphone provider and if they didn't have a solution, you would be referred to the manufacturer's support channel. If you were lucky to talk to someone, it would be a Chinese person with broken English and dry attitude.
On the contrary, Apple continues releasing updates for all their models during several years, sometimes more than 5 years. Why? It's because they have their Ecosystem, with the AppStore, iCloud, etc. That revenue pays for Tech Support, Software R&D, Software Updates, development tools, AppStore hosting, iCloud hosting, etc. And remember Apple stopped charging for their OS updates too.
The hardware revenue covers the cost of retail stores and employees, R&D, advertising, etc... So when people say: "Oh, Apple only pays $400.00 for a device they sell for $1200.00, they are soooo greedy!", they don't know what they are talking about.
These new Gens are spoiled to the max, I don't want to imagine what the next one will bring; probably more whining and demanding, because they deserve it all.