I used to think the same thing until I turned on my nearly-new Samsung TV only to find their proprietary Smart TV had deleted a pile of apps, including CBC All Access and in order to use my streaming services, I had to spend $50 on a Roku dongle and lose an HDMI slot.
Amazingly, the cheap Hisense and TCL TVs, with non-proprietary Roku Smart TV handle it no problem and have a ton of apps.
Trust me on this, DO NOT buy a Smart TV with a proprietary interface - stick with branded Roku, Fire TV, etc. models, as companies like Samsung and Sony didn't want to pay for a reputable Smart TV service like Roku or Fire TV, but they also do not have the manpower to actually develop and support their own Smart TV software, so if they find a problem, they just delete the apps rather than fix them. Then next week the cheapasses find more problems and just delete more apps. Then soon all you have is Netflix and Prime TV... at least until those start giving them trouble too.
And as the lady on Samsung support told me, "if you lose an app, it's not coming back, ever."