This issue (why doesn't everyone use a receiver all the time for sound) has been discussed to death here. Sufficie it to say, to each their own. You are considering the world only from your unique point of view. There are many, many people who want a TV, not a monitor, and either want or need (or both) to have it function as a stand-alone device, sound and all.
I know in my household, we use both. I have a Denon 3808ci AV receiver with nice KEF speakers. But 90% of the time, the TV is still viewed without this system turned on, and that how my wife and younger kids prefer it. And, yes, I have a Harmony One remote with all the macro commands fine tuned to make turning the TV and receiver and sources on correctly with one touch of a nice color graphical button and it makes absolutely no difference.