It’s already been said quite correctly. If all you watch is Netflix, Hulu, amazon, and the likes, then the built in apps of the LG OLED are fine. Albeit in my opinion not the best quality compared to the media streamers. And definitely not the best audio, being the internal apps can only get their audio out either through the ARC or optical. Media streamers go straight to your avr if you have one, and the audio will be better.
Now, having said that, if you’re looking for the best media streamer to pair up with your LG OLED, it’s obviously between the Apple TV 4K and the Roku Ultra. Both have their pros and cons. Roku is pretty much the industry standard, and all the apps you can imagine pretty much are there. But, Roku lack Dolby vision but does have Atmos. ATV4K has Dolby vision, but it doesn’t have Atmos, yet. It is suppose to get it this fall. ATV4K can sync with your iTunes, has the ability to get other media as well as your existing iTunes library and such. The Roku has very reliable HDR on certain apps like Netflix. The list is endless. Some will say the Roku is better, and some will say the ATV4K is the best. Definitely go to those forums to figure out what’s best for you. But if you want to maximize your LG OLED tv beyond the limitations of the internal apps, then yes, you need to get a media streamer like the Roku Ultra or ATV4K. If you’re content with the picture and audio quality of the LG OLED TVs internal apps, and don’t need more or better quality, then save your money and enjoy your tv.
In the end, it’s all about if you’re happy with your tv. If you really like the picture, then you DON’T need to get it calibrated. Don’t ever let anyone tell you you’re tv isn’t set up the way it’s SUPPOSED to look. If you like the picture and are happy with it, then it IS set up the way it’s SUPPOSED to look. If you watch the basic apps, and they are included in the TVs internal selection, and that’s all you care for, then that’s what you should have. Don’t let anyone tell you you should, must, need, etc. a Roku or ATV4K. You don’t. If you play an app, blue ray, cable, satellite, etc. and use the internal speakers or a sound bar, and you are enjoying it, then don’t let anyone tell you you should, must, need, etc. an audio/video receiver and a 5.1, 7.2, or Atmos setup. You don’t.
Is a media streamer better than the internal apps? Yes. Why? Many reasons. Is an avr better than the internal speakers or a sound bar? Yes. Why? Many reasons. You need to decide if what you have makes you happy and content, or if you want more. If you are content, then enjoy. If you want more, go to the appropriate forum for avr, media streamer, UHD blue ray players, etc. and determine what’s best for you.
But remember..... there is no end game of what is right or best. Is my 5.1.2 Atmos setup the best? For me..... and the room I have to work with..... and the amount of money I want to spend. it is the best. Some people have their OLED tv and simply use it to watch cable or satellite and dvds. That’s good enough for them. Some spent the money on an OLED tv and their main use it to play games. That’s good enough for them. Some want to totally cut the cord from cable or satellite and don’t like going to the theater to watch a movie. So for them, they add to their OLED tv an AVR, a media streamer, a 4K blue ray player, 5.2.2 or 7.2.2 speaker system. And that’s good enough for them. In the end, YOU have to decide what is good enough for you. Don’t let anyone else tell you what you need or should have. Then go to the appropriate forum and educate yourself.
Best of luck, and most importantly, ENJOY your tv.
LG OLED65B7P, Yamaha 7810, 5.1.2 ATMOS
Philips 7302 BR/DV, ATV4K, Roku Ultra, Roku Premiere, Roku Stick+