At first I was going to disagree, because having the compute built into the TV makes some sense, but thinking about it made me change my mind.

A modern TV has a lifetime of 15 - 20 years I think. E.g. my in-laws have a Sony TV, from around 2012 - 2013. It's not 4K obviously, but the picture is beautiful, the sound perfectly fills their small living room, it's a great TV. Even considering that Sony did skimp on the compute in that TV from the start, there's no way that they could have put in hardware that would future proof it until 2030 or beyond. Nor could they reasonably charge enough to cover software updates for that long. It makes much more sense to have a replaceable external unit.

Fortunately you can still by an external unit and plug it in