Nobody here's saying anything like that, though. Not sure how you got that idea?
But if the OS on your TV isn't being updated by LG any longer, then you won't be able install the newest versions of many apps, since they use SDK-features, that aren't supported by the older versions of the OS.
Whether an app is actually developed by a third-party, like the BBC or HBO, doesn't change the fact that "minimum supported OS version", is as crippling for a TV, as it is for a smartphone or tablet.
Last time I had to buy a new smartphone, even though the old one was still in excellent working condition, was because my bank and mobile payment apps, stopped supporting the Android OS version, it were stuck at.
I'd hate to also have to buy new TV's, just because the Netflix, HBO, or whatever apps I use, stop working.