That's fine, but even among Android users, nobody buys these removable battery phones. It's possible there's a disproportionate reservoir of iPhone&removable battery-only consumers, but it would surprise me if the desire for a reusable battery were strongly correlated with being locked into the Apple ecosystem. If anything, I would expect the propensity to desire removable batteries is more strongly correlated with Android use.
There are a plethora of reasons to prefer one phone to another and while removable battery phones exist if that's a strict criteria for you the market of available devices is extremely limited. Consumers don't have a real choice here.
I would expect that one of the main reasons that people prefer non-removable battery phones are the engineering tradeoffs inherent in making a phone with a removable battery. They will have strictly less choice on this axis when they no longer have the option to buy a non-removal battery phone.
I think you are vastly overvaluing how much consumers actually value phone thinness. The majority of consumers use phone cases (most modern phones have a camera popup specifically to be better compatible with a case to this end) so I think what customers value the most is lighter weight - not smaller form factor. A replaceable battery does come with a slight compromise to weight but stopping the endless chase of thinness has several engineering advantages when it comes to ports and cooling.
I don't think your speculation is completely unreasonable, but I just want to point out that consumer preference as revealed by current, actual reality only provides evidence in favor of my side of the argument. It's totally possible that the manufacturers are completely wrong about consumer preference and they are acting against their own interests by making the batteries non-replaceable, and somehow none of the manufacturers noticed this or were able to successfully take advantage of it to gain market share. But, I think that would be a pretty surprising thing if it turned out to be true.
Usually, in consumer electronics, the unencumbered market tends to gravitate toward what people actually want to buy. Totally possible this could be an exception to the rule, but I doubt it.
Such phones exist, for Android. Several companies* make highly rugged phones. You can drop a Blackview BV7000 down a concrete staircase, watch it drop into the ocean at the bottom, have lunch, come back, and retrieve your phone from 40" of water, likely completely undamaged.
It's an extreme example, and way too bulky for most people, but the point is: "rugged cellphones" absolutely exist.