Is there any reason you need exactly these "top tier" devices? For under $200 there is well-built Xiaomi devices with 3-4GB RAM, powerful CPU and everything except for removable battery.
Of course you should never use firmware from Chinese company, but it's true for 98% of other Android devices too and LineageOS + microG work great on these phones.
Because mobile phones are complex beasts hardware- and software-wise, and going top tier makes it much more likely you'll have a fast device for years, that works with whatever random idiosyncratic software and hardware you throw at it.
Like, e.g., last year my SO was changing phones, and we didn't have much budget left, so we went with then-recommended Huawei P8 Lite. Almost good enough, except it seems to have its Bluetooth stack broken in a very specific way that renders her Pebble almost useless. Oh, and every other day, it randomly drains battery very fast. It's those kinds of things you generally don't have to deal with when you go with higher-end devices.
Might be I was just lucky with few devices I owned over last 5 years, but I only got problems with them after putting them in some insane conditions like living in Asia with constant overheating, sand and sea all around. Though I only ever used Cyanogenmod / LineageOS and specifically was looking for older, but tested devices that work well with custom firmware.
Also when it's $160 device I don't need to worry about randomly died battery because I can always get new phone.
No, not really. I'm personally an iPhone user, but my wife has a really nice Android phone. I like top tier phones even though they're more expensive. That said, I didn't want to spend so much (or wait) for an iPhone X, so I updated my iPhone 6 to an iPhone 8.
Genuine question.