I just bought an LG C1, upgrading from an 7 year old Sony TV, and it has all streaming apps including Apple TV built in. The Fire TV stick can be had around $70 with all streaming options as well. Buying these external streaming devices can also be clunky as I have a PS5 and a blu ray player connected to 2 other ports, so an external streaming device means I have to constantly fiddle with my TV remote to turn on the appropriate port and then switch to the device remote. It’s so much easier to just push Netflix on the tv remote and be done with it.
What is the selling point for paying $180 for the ATV 4K when the TV itself and Fure TV can get it done for basically free?
Your new TV will likely last at least 10 years if you take care of it, although you might replace it before it reaches the end of life. However, after a few short years at best, the manufacturer will most likely stop making major updates to the software and eventually newer apps won't play on it because it's firmware has become out-dated. Plus eventually the hardware will be at least somewhat out-dated. So I find it is better for me to buy the streaming boxes rather than rely on the TV's apps. Apple does continue to update the ATV models for many years, and they are much cheaper than a good TV, so more economical in the long run.
When you buy your TV it might come with a specific version of app streaming. For example, it might come with Roku, Fire TV, Android TV, etc. built in, but only one of them. I prefer a little choice. For example my Sony Bravia came with Android TV 9, but I also have a Fire TV Cube 2nd gen and my ATV 4K 2017 plugged into it. I have Prime Video from Amazon as part of my Amazon Prime annual subscription, and Prime Video works best on a Fire TV rather than using an app on the TV or ATV.
I have plenty of other Apple devices including Mac, iPhone, and iPads, so I like the seamless integration they have with the ATV. I can look at my photos and videos, mirror a device, etc. all very easily with the ATV.
I also like the ATV 4K hardware as it is better than the Fire TVs, Rokus, and the FW on my Sony Bravia that runs Android TV. I don't subscribe to TV+, but if I did it would look best on a ATV.
Bottom line, cheap doesn't usually translate into better. It usually translates into barely acceptable. I prefer a good quality of streaming, and getting a ATV 4K is how I get that. Ditto for the Fire TVs and Rokus. They all tend to be better choices than running apps on a smart TV.