The difference between your technically-grounded assessment of the phones produced by Samsung and the assessment of more regular folks is staggering.

It'll take a lot more than a few vendor-specific OS tweaks to put non-tech people off.

To be clear, I agree that the OS modifications implemented by Samsung feel like they result in a less performant experience.

Warning: anecdata below!

My girlfriend's family regularly use various tech devices (laptops, phones, tablets) and are technically literate in the use of such devices for consumptive purposes and I'd rate them as relatively technically illiterate in the use of tech for creating anything beyond simple MS Office-type documents.

As a generalisation, they pay zero attention to the tech media (I'd say they are largely unaware of tech media sources), obtain all tech news via mainstream media and are influenced by both mainstream and Facebook advertising which they don't see as advertising but as useful information.

They have strong brand loyalty or, more specifically, they have a definite preference towards brands they believe have served them well in the past.

They all generally opt for Samsung phones. This seems rooted in prior positive experience with earlier-generation Galaxy devices.

They appear not to differentiate between Samsung's Galaxy line and Samsung's other lines of lower-priced smartphone ranges, suggesting a bias for the brand over the hardware/software combo itself. Their choice of phone contract seems based on Samsung and price almost exclusively.

I have seen them switch from technically better to technically worse hardware and still be pleased with their new phone. A new phone is often perceived as better than an old phone purely due to it being newer.

My girlfriend's mother used Sony phones for years predominantly based on her positive experiences with the Sony brand in non-related lines such as TVs.

She switched recently to a Galaxy S8 when her contract was up for renewal. Her decision was based mostly on the preference for Samsung phones in her immediate family. Her only issue with it was the dedicated Bixby button and her issue was not with Bixby itself but with her unsteady hands pressing the button unwantedly. My girlfriend disabled the button and her mother now perceives the phone as the best thing to have ever existed. She bought a wireless charger, again due to her shaky hands being unable to cope with plugging in a charging cable. The positive association with the wireless charger further reinforces her positive opinion of the S8 regardless of the fact that wireless charging exists across many phone brands and ranges.

The bloat of vendor-specific OS modifications is a non-issue. If the bloat factor is consistent, a phone today is faster and better than a phone of two years ago.

They see smartphones grouped into three families: iPhones, Android phones and Samsung phones. That the OS on a Samsung phone is based on Android is not considered. That a phone may not get OS upgrades in a timely manner, or at all, is a complete non-issue for people that don't know that such updates exist, don't generally care about the OS and who replace their phone every two years.

Similar to how many get a Windows upgrade only by buying a new computer (although less-so now with Windows 10 but more so historically), many get an Android OS upgrade only when getting a new phone. That a phone should get, or needs to have, OS upgrades is also a complete non-issue.

In short, for those not close to the tech industry, there is nothing wrong with Samsung phones. The common gripes we in the tech field often mention (slow/lacking updates, under-performant UI tweaks aka lack of purity) are so much of a non-issue for the majority of Samsung phone users to make effectively zero difference to Samsung.

[Editted for typos]