The difference is those other manufacturers have a wider product range allowing them to cover more bases. Ones requirements will generally dictate which approach one prefers.
I don't like to visit restaurants with large menus, trying to encompass every taste, as I'm often concerned they'll never perfect any of them. But equally it can be very disappointing when I find myself at restaurant with a small menu if I don't like the items on it, regardless of if they do those dishes to perfection :/
With their small product range they have to make a choice and I suspect they have made the right one. I'm pretty sure the "upgraders" are vastly out numbered by people like my Mrs who simply see it as a technologically (in terms of hardware) static product like our TV.
I don't think the vast majority of their users ever upgrade their machines (other then perhaps the HDD/SSD). I also doubt many would ever use more then one battery (as a road warrior for several years, I often purchased extra batteries, but forgot to take them with me or charge them, or found leaving the one I didn't use often fully charged caused it to fail more quickly). And yes paying Apple £109 to replace the sealed battery is probably double the price of OEM batteries for laptops with user replaceable ones. But in the grand scheme of things £50 extra every couple of years is not going to make someone paying a premium already flinch.
Apple definitely weren't the first to do this, I can recall Toshiba and Asus machines with Soldered RAM from a decade back. Where this approach falls down is when the SKU's aren't equipped with enough overhead to cover the useful life of the machine. If the RAM is sufficient to keep the machine ticking along nicely for 4 or 5 years, do most people really care?
Of course others may be right and Apple could be wrong. Perhaps they have taken a wrong turn and will fall flat on their face. They've done it before
Perhaps MS will stop floundering or maybe Google, or some new entrant who they don't think could be a threat will knock them of their perch. But right now they're sitting pretty and I (along with many others) don't find the lack of upgradeability a major issue.
