Apple has been doing what you've observed for years.
As for leaving the ecosystem, I've done it... but that doesn't require ditching Apple hardware. I still have my 2013 and 2017 iMacs (the 2013 serves as my Plex server and 2nd monitor to my 2017 iMac). I have an iPad Mini 5, iPad 9th gen, and iPhone SE 2.
That's the key these days, IMO. Forget the FOMO (fear of missing out) of not having quad speakers, pro-motion, etc. and go for the entry level products. The iPhone SE and base iPad offer some of the best tech bargains available.
I have chromebooks, Windows laptops, Android tablets, and countless other devices in my regular mix, and these Apple products work well together. As a result, I have spent far less for far more tech than those who are all-in on Apple's top tier products and services.
But that's me... I'm a bit of an oddball. But if you'd like to get into the details of how something like this can work for you, I (and others in similar situations) would be happy to help.
I won’t leave the ecosystem, but I don’t buy new devices all the time (I buy pretty infrequently, actually), and I think what you propose is very interesting.
You can even stop buying new! I (try to, if Apple allows me...) leave devices on their original iOS versions, or, if possible, on the earliest version Apple will allow. They force me to update? (Like it happened when they forced my 9.7-inch iPad Pro from iOS 9 to iOS 12), it stays there (I had an updated iPad three years ago, now it is four iOS versions behind. While battery life is bad compared to iOS 9, it is a lot better than it will be on iPadOS 16).
If I do that, devices maintain top-notch performance for years. If the user’s usage patterns don’t change, they can be used for many, many years. Buying new is cool, but not necessary. I keep devices for many years, and as long as Apple doesn’t force me, it’s fine.
I recently bought an iPad Air 5 to upgrade my 9.7-inch iPad Pro. The only reason for which I was compelled to do that is Apple’s forced update. Otherwise I would’ve been fine. Hell, if I weren’t so obsessive with the motto of “my devices should work exactly as I expect them to, otherwise I don’t like them as much anymore”, I could still use the 9.7-inch iPad Pro. I use the Air in the exact same way. The Pro works just fine! The 20-40% dip (depending on the cycle, it varies) in battery life bothered me a lot, and that’s the only reason I upgraded. It still gets 8-11 hours of screen-on time, so if I were happy with that, I’d have no reason to upgrade. I use the Air 5 in the exact same way I used my 9.7-inch iPad Pro. I don’t need new.
I could use my iPhone 6s on iOS 10 as a main phone just fine (if it were 128GB like my previous 6s, which was on iOS 9 and was forced to iOS 13 due to the same iOS 9 on A9 activation bug, it‘s 32GB, it’s a little tougher), but only now am I losing access to one important app. Go back to, say, last year, and I’d be able to use it just fine. I don’t even need new devices, they work for years. Battery life on my 63% health iPhone 6s on iOS 10 is like-new (yes, 63% health. 7.5 hours of screen-on time on Wi-Fi), and I use my iPhone Xʀ (on iOS 12, of course), just like I use my 6s. They work for a very, very long time if kept on their original iOS versions, and app support’s impact is wildly - very wildly - overstated. It takes many years for it to reach critical level, and barring some specific cases, if you download everything you need it doesn’t even matter, assuming usage patterns don’t change.